I'm sorry to hear this. My cat Storm was diagnosed with small intestinal disease,a form of IBD, several years ago and he's now 16 years old. He was vomiting his food up too. He's been on 2.5mg of prednisolone every morning and he's doing great. He and my 4 older cats eat Wellness Core dry which is grain free and they also eat some of the Wellness grain free canned in the Chicken, Turkey, Chicken&Herring, and Turkey&Salmon. I tried Natural Insticts a while back i both dry and canned and at first they loved it but then they didn't really like it and I also found it to be very expensive for what it was. I know that many people don't like to put there animals on pred but sometimes it's the only thing that really helps. Good luck.