I'd highly recommend you (and he) read Jini Patel Thompson's book Listen to Your Gut. This is the most comprehensive book - really a reference manual - I've found detailing all types of alternative and natural treatments for IBD, including dietary recommendations to address varying levels of symptoms. It discusses probiotic supplementation and natural supplements that are healing for an inflamed gut.
I do agree with the other posts that stress reduction is vital... even if it means taking a different job or taking a sabbatical. I went from a stressful ad agency job with a horrendous boss to a laid-back state job, working with great people. It makes a huge difference.