Well, the best recommendation in my opinion is raw food for IBD (but not just any commercial raw because most commercial raw foods have way too much bone which is not easily digestible). It may be worth doing some research and preparing your own if you are willing to take the plunge... currently in that boat myself.
One commercial raw brand that might be good to start with is RadCat. They use eggshell powder instead of bone so it may be easier to digest.