Can't figure out what's wrong.

So when we first adopted my cat at 9 months from the shelter, we noticed he was pretty gassy. We tried a bunch of different foods to see which made him not ...in lack of better terms..fart. I really wanted to have him on Blue but it gave him problems so we feed him Hills T/D and gastro fibre. He used to have bloody poops, but when we brought him to the vet they said he possibly has IBS and since we switched

to vet foods we rarely often have to wipe his bum of blood. It's very rare, maybe once every 3 months.

So recently, over the last 6 months, Spinner, my cat has had very random spells of vomitting and not eating. He'll throw up maybe 7 times in the span of a couple days, throws up his food, and if he doesn't eat, just water/bile (i assume bile is in it) And I guess he throws up so often he just doesn't want to eat. So then he stops eating for a couple of days, and then he'll get constipated. One time he didn't poop for 5 days and when we called the vet they said bring him in the next day and that morning he pooped. (lol I guess threatening to bring him to the vet de-clogged him) 

We recently went BACK to the vet to see what the heck is wrong with my kitty, we're not made of money, and the vet gave us a lot of options, so we chose the feline ADR check plus with spec fPL, We got a call the next day and they said everything was fine except that his white blood cell count was low. I'm going to book him for a CBC test this week but really...all this inconclusiveness drives me nuts!

Has anyone had a similar experience? Thanks.

Many people have, actually.

You might want to read this thread: http://www.thecatsite.com/t/267197/cat-food-cat-stress-stress-related-ibs

My guess is that his gut flora is all out of whack. I'd give him at least an L. acidophilus supplement (probiotic), and I would consider feeding him a meat-based canned food that has very few other ingredients.

You might want to try using this supplement if you transition him off of dry onto a wet food diet:
But I think digestive enzymes and a probiotic will go a long way to helping him. It can be hit or miss as to the right probiotic, but L. acidophilus is a good place to start. I give my cats 1/2 of a capsule, 2x a day. The one I use is Natural Factors double-strength acidophilus+bifidus (in a goat milk base).

A low white blood cell count can be caused by so many things.... but as the GI systems represents approximately 70% of the body's immune system function, providing healthy bacteria will help improve his overall immune system function.

Thank you. The vet also suggested we switch to venison/bison/rabbit wet food something about proteins he hasn't had yet. Now I see that wet food may be the better option for my kitty and his problems. 

I am interested in probiotics for my cat. What are some options to get probiotics into my cats diet? 

To help you understand about a cat's nutritional needs, this site is written by a vet and is easy to understand: http://www.catinfo.org

To use the probiotic I mentioned earlier, all you have to do is sprinkle half a capsule on your kitty's food in the morning, and the other half in the evening. If you're in the U.S., it may be available in a local health food store, but I order it from Amazon (it's cheaper for me).

There's one specially formulated for cats called Benebac. I've never used it, but it's helped others' kitties.

Digestive enzymes might also help him. There's a discussion here: http://www.thecatsite.com/t/265741/digestive-enzymes

Many of us use Prozyme original. It takes very little - just a small pinch sprinkled on the food at each meal. Again, I order it from Amazon, though it's probably available in some pet stores. But I provided a link to a product specifically designed to help prevent stomach upset during food transitions. It has digestive enzymes in it, and is designed for cats with sensitive stomachs. It's called Holistic Transitions. I know it's available on Amazon.

There are options for novel proteins that also have few ingredients that would cause an upset tummy. Many of the options are discussed in this thread: http://www.thecatsite.com/t/262990/carrageenan-free-canned-foods