Crohns seems to vary alot person to person in severity and triggers.
I have 2 friends, both sisters, that have Crohns. One eats really spicy foods all the time, one can't. One gets reall bad intestinal discomfort and ugent attacks, the other doesn't seem to have any pain but has alot of bleeding.
As far as the IBD / IBS probiotics seem to help alot.
I had a really bad GI infection that went unchecked for 2 years due to misdiagnosis. I couldn't keep any food down or in for a while. Not quite the same as IBS / IBD but alot of the same symptoms. On my 3rd GI doctor I started taking this
http://www.vsl3.com/ and it worked wonders. Not cheap, but also not something you should buy unless you're really ill either. It wasn't an overnight change but it gave me my life back for sure.