I can't help on the food front (Marsh was a kibble addict). But here's some info I put together on probiotics and digestive enzymes when I thought she had IBD. She was initially diagnosed with IBD but it was later determined to be either gastritis or stomach lymphoma. Hope some of it is helpful!
There's a Facebook group called IBDKitties. There's a lot of good info on there but it can be overwhelming. The woman who runs that group also has a site called ibdkitties.net. The FB group is where I first learned about digestive enzymes and probiotics and they told me to start with the enzymes and then progress to probiotics.
Digestive enzymes help kitty digest the food so they use more of the nutrients in the food. Start small, and work up to the recommended daily dose on the bottle (best if divided into however many meals you feed and added to the food at each meal time). You will want to make sure none of the ingredients bother her, so start with digestive enzymes and after kitty is up to the full dose and tolerating it well, then maybe add probiotics. You will know if kitty is tolerating it if there is no vomiting, no mucous in the stool, or anything else that indicates it’s upsetting kitty’s system. If she tolerates and does well on those -- and you should know inside of two weeks -- you should see smaller stool, slightly harder, but not constipated. Less volume of stool means she’s using more of the nutrients in it.
I used Animal Essentials Plant Enzymes & Probiotics. It's available from Chewy.com or Amazon for about $10. There are a lot of reviews about how it helps pets with diarrhea. Marsh didn't have diarrhea when I used it but I noticed her fur got a lot smoother and glossier, so it was doing something! I gave her 1/4 tsp once a day but I think you're supposed to give it twice a day, mixed in food. Since she wouldn't eat wet food, I mixed it into pumpkin and syringe-fed it. Keep it in the fridge to make it last longer.
Probiotics
S. boulardii is a yeast-based probiotic that does not colonize the gut. It helps displace unhealthy bacteria, promote growth of healthy bacteria, and helps normalize intestinal function. It has anti-inflammatory properties, and passes through undigested and works locally in the lumen of the gut. If you stop using it, it will be completely out of the cat’s system within 36 hours. It is more beneficial when diarrhea is the problem. It can taste bitter to some cats, so you might have to put some in a capsule and give it to kitty in pill form. Some cats will take it mixed with water in a syringe.
The other probiotics are bacterial and help colonize the gut with healthy flora.
Lactobacillus acts in the intestines (which tend to be responsible for vomiting and constipation) and
bifidobacterium acts in the colon (which is usually responsible for diarrhea).
Acidophilus helps amino acid uptake and utilization of B12. All of the above can be mixed into wet food at each meal and are flavorless.
For specific brands and doses:
http://www.ibdkitties.net/Probiotics.html
Some of the brands on this link indicate which probiotic strains are included but others don't list the kind of probiotics.
I gave Marshmallow Renew Life Ultimate Flora (15 billion CFU), 1/4 tsp, once daily. It has lactobacillus and bifidobacterium. She alternated between constipation and diarrhea, which indicates a tug-of-war between issues in the intestines and issues in the colon so theoretically that combo should have helped her. I only started giving it to her towards the end but when she got really sick I stopped because I was giving her SO many meds and pills and syringes that I only wanted to force the most important things into her. The Renew Life comes in capsules so I'd break open a capsule and there was enough in there for about 2.5 doses. Keep it in the fridge to make it last longer. It's on Amazon for $27 for 60 pills. I think I got it for about $25 so that's about the standard cost.
http://www.amazon.com/Renew-Life-Ultimate-Formula-Capsules/dp/B0042L1S1S/?tag=felinediabetesfdmb-20
