2 Shelter Kittens Chronic Diarrhea

Hi. I have 3 kittens, all about 7 months old. 2 females were adopted from the shelter, 1 male was a stray I began feeding as a baby. They are all inside / outside cats. I recently began making them stay in more at night, so I've noticed the litter box. One female - Orange has had chronic diarrhea for at least 2 or 3 months. It is liquid, or like baby food. She runs and plays and seems happy. I see her eating grass a lot lately. She meows more. She's had 2 courses of antibiotics. No change. Other female - SC came home from the shelter with horrible diarrhea that day. It cleared up for a while, and now is back. She seems less frisky. Also liquid. Tom the male so far does not have it. I have noticed if I leave them home alone at night, I'd come back to cat pee in places other than the litter box. So I bought 2 additional boxes now have one for each cat. SC smells awful. She appears clean but smells like poop.
The vet now wants to change their food. I feel like its a bigger issue. They've all been dewormed at least once. Shots utd. All fixed. No throwing up.
I am poor and cannot afford endless vet visits and ineffective medicine.
Any advice ?

I would really recommend keeping them indoor only from now on. Since they're young, they will adapt pretty quickly to the lifestyle, and if you want you can train them to wear a harness and go for walks, but if they come and go they can get all sorts of parasites very easily and you have no way of knowing where or how they got them. It's very dangerous no matter where you live for outdoor cats, which is why indoor/outdoor cats only live to be about 5 years old on average. Disease, predators, other cats, cars, chemicals like antifreeze...the list of threats is lengthy.

There are many common parasites that cause diarrhea that kittens seem especially prone to, and they're not like a virus where they can only get it one time-they can keep getting reinfected with the parasite as long as they are exposed to it again, even if they've already been treated for it. But if they don't go outside, the chances of re-exposure are slim. What color is the diarrhea? Do you know the names of the dewormer medications that they've had? 

Parasites are what I think of first when kittens have diarrhea, especially those with outside exposure. The most common are coccidia and giardia. Coccidia tends to produce runny stool with a yellowy color, whereas giardia is more normal brown diarrhea. Some kittens end up with both or more. There are different medications that can be given for each of these. You also might want to keep the male separated from the other two for a while, because cats who share litter boxes can catch these parasites from each other. It might not be parasites, but I've only had experience with routine shelter care, so otherwise I'm not sure what the next best step is. Regardless, they stand a much better chance of getting better indoors! 

What food are you feeding? Kittens have very sensitive digestive systems so If you're feeding something that their system doesn't agree with you'll get tummy issues. A lot of low quality kibbles are loaded with fillers that can aggravate kitten's sensitive tummies. Obviously you should rule out all infections first. Have you had a fecal done to rule that out? 

I'd suggest giving your kittens a daily probiotic mixed in wet food. I give all my kittens (and cats) a daily probiotic. Here's a link to different ones you can purchase that are safe to give to cats/kittens. 

Thanks for advice. Tom and SC have regular stools now. Still checking on Orange. I'd been feeding them Friskies, but after reading through this site, I realize that's like the fast food of cat diets. I got them Royal Canin for sensitive tummies yesterday. They actually seem to like it a lot more anyway.
I still let them out a little while but not for long. We have such a small ( 800 sq ft) house, I hate keeping them in all the time. I've got some Revolution medicine I'm going to start them on tonight also. I was scared to use it when they were younger, but I think they're ready. If Orange doesn't improve, I'll order the stool test to be sent out to a lab as I read that's a more thorough method to detect things. The test the vet did was negative but I don't even know what he checked.
I'm a new cat owner and just didn't know some of these simple things, like each cat should have their own litter box. Thank you guys.

Sometimes they make this weird kind of choking cough sound but never throw up or cough up anything. Is that just to do with hairballs? Its just every once in a while.

I had multi cats in a 600 sq ft apartment and they did just fine.  Please consider keeping them inside and investing in a cat tree for them so they have some vertical space.  It'll really be safer for them in the long run. 

As for the diarrhea, I"d have the stool tested using the PCR diarrhea panel.  It's more comprehensive than the fecal float done in the vet's office. 

If you're feeding dry food, be careful when you switch and do it very gradually. I would recommend feeding them a grain-free canned food for the bulk of their nourishment.  Even the classic Fancy Feast are grain-free. 

Thanks. I fixed up a scratching post type thing for them and am going to be investigating further. I'm on a very tight budget. I did purchase a second grain free food for them called TruFood. The vet recommended the RoyalCanin, but if that doesn't go well, I've got that backup ready. I have been reading more about cats in general. So much conflicting information. So I've moved all the house plants and hung up the blind cords. I've stopped burning wax melts and scented candles. Each cat has its own litter box, food bowl, and water bowl. They all have breakaway collars and plenty of toys.

Good call on switching food.  Friskies/Whiskas is kitty crack but about as healthy as heroin.  A great grain-free pure protein that mine LOVE is Instinct.  I mix that with wet Royal Canin (about 50/50).  They need the dry food also to have enough fiber in their diets.  However the wet is good for yours since its mostly water and dehydration is a concern with diarhea.  

One thing my vet told me to do was to sprinkle human probiotics on the wet food.  My cat has no clue shes eating it because its flavorless and it helps her digestion and overall health.  I dont do it always, but definitely when shes not 100%.   I use a liquid probiotic called Sinuberase (only available in Mexico) but I am positive that you can find a similar version.  Don't give her a human dose, just a few drops on the food and voila.   

If you are concerned about dehydration, consider giving them a tiny bit of tuna water (the water you drain from the can of tuna before eating it) mixed with regular water to cut the sodium.   Make sure its tuna in water and not tuna in oil though, the oil is bad for them.  

FWIW when I got Bud, he was sickly, his coat looked bad, and he had diarrhea constantly. After a week or two of Blue Buffalo dry food and quality canned food, he had solid stools and started to look much better. Obviously the people I adopted him from did not do a very good job taking care of him.

So yeah, food can have a lot to do with it. But I have no real expertise in this matter and would defer to what others -- and your vet -- are saying. All I know is that decent food did the trick for my cat when he was a baby.

So I'm taking Orange back to the vet tmrw for a giardia test. If that is negative, they'll do a PCR test to send out that checks for a single thing. We'll see.