Help please!

I have three cats and my roommate has two of her own, everything was fine until her cat started puking consistently for an entire day. Then one of my cats started vomiting and now all five of them are. It has been three days now since the start, the vomit is either clear/white with spitty foam, yellow, a browish, and one cat vomited a reddish color (like a melted cherry Popsicle color). I'm incredibly worried and have a vet appointment set up on the 5th (it's the 3rd now). Food has been taken away from them to let their bellies settle but that doesn't seem to be working, water and a water/pedialyte mix has been set out (after giving them 6 hours without like an emergency vet instructed).

all of them have had Meow Mix as their food, regular water to drink, and cats pride litter to potty in.

here are all of their symptoms: 

Suzie:

-Seal Point

-1 year

- For around a month or two has had diarrhea, we've been working with the vet to get it under control but bow she has uncontrollable, watery stool that has had red in it but not the coffee ground red. It is so wet she cannot control when it comes out and it just falls from her. Her backside is raw from her licking it so I have put a cone on her to keep her away from it, she seems otherwise fine, maybe a little tired but not so much so as to be extremely out of the ordinary.

-she puked twice both times it was yellow, once had food in it.

MiMi:

-plain tabby

-1 year

- she puked once and it was yellow but otherwise seems fine now

Chichi:

-Tortie

-7 months

- diarrhea

-puked 3 times with some being the white foamy and others being a brown/yellow

Simon:

-Long hair orange tabby

- 9 months

- He has had chronic diarrhea since we got him. We have been working with the vet to try and fix this, we've tried all the different wormers and now they want me to try that purina flora stuff you sprinkle on their food. His diarrhea has persisted though it strangely got thicker? and darker in color. Again not the coffee ground color of blood but a dark, almost normal poopish color? Like melted chocolate as gross as a comparison as that is. No worms have ever been visibly present in his poo before or now.

- thrown up too many times to count between white/clear foamy, brown, yellow and seems to be in pain when he does puke. He does meow a lot (hence the name: simon ((simon says)) so I don't know if he is in pain or just whining because he is obviously uncomfortable and doesn't want to get sick. I know cats are masters at disguising their pain so I worry a lot)

Nightwing:

-Long hair all black

-9 months (simon's sister)

- regular poops but is puking just as much as simon with the same symptoms: whining before hand, color ect.

I would love any feedback on what i should do/ say to the vet. I think I want to have them checked for giarda, i was going to call tomorrow and get a price estimation for a complete physical exam, fecal analysis, and bloodwork to get them back on the right track but if anyone could give any information they can think of or any suggestions on what else to ask about that would be fantastic. i'm really concerned about my babies and I just want them to be okay.

Is the food the same food you have always gave them?  If so, is it a new bag you just opened?   Maybe something is wrong with the food?  Any plans new to the house they could of "chewed on"?   I would think it has something to do with the food since it is suddenly happening to all of them.  I know that sounds to easy, or a why would it be food, but if its a new bag or a new kind you switched to, may have something to do with it.  Tainted bag possibly.   I hope things get better.  

Thank you for your reply! I have always fed them meow mix and never had any problems until we got to around the end of this bag I'm really really hoping they get better, their vet appointment is later today and I'm keeping my fingers crossed that it'll be an easy fix like a shot of medicine and some take home stuff and not anything serious like surgery. They are our babies and I hate seeing them so unhappy (((

I would say too it is most likely something they have eaten or drank. Is their water fresh? Could they have drank out of a plant saucer or the toilet? Like stated above, any new plants? Any new toys? My cats vomited a lot until I started them on a 'sensitive' stomach food, you might want to try it. The Meow Mix may have changed their formula. If it's a 'kitty flu', it may have to run it's course, but L-Lysine treats to build up the immune system wouldn't hurt, you can get them at Amazon. Plain yogurt helps with the digestion, as does a couple of tablespoons of plain canned pumpkin, which might help with the diarrhea.  You still need to find out what it is,and only a vet can help,you there. All the luck!

My cat had been vomiting for 2 days and my boyfriend cooked her plain boiled chicken, and fed her some just  a little at a time. It seemed to help as she was hungry.

She also has bouts of loose stools like your Simon. And she poos on the floor when she has loose stools (as if she doesn't want to get her tray dirty). The vet couldn't find anything wrong with her and thinks she is just sensitive. She eats everything she can so we have to be careful with food we leave lying around. She will eat flaming hot Doritos (her fave), bread, cheese, butter. She once jumped up and stole some chicken curry from my boyfriend's fork. And when's she's outside, I'm sure anything goes!

Do your cats go outside too? It's really hard to control what they eat when they go out and Chica is a great mouser.

Super late update post:

It turned out we got a very messed up bag of meow mix, since this incident I've switched their food, they eat Taste of the Wild and Iams indoor cat formula now and all are good and chunky with none of those ailments which I'm so thankful for!