B..
I don't know if it's an option for you, but have you explored any alternative medicine?? I used to be a chiropractic assistant. We saw some people with IBS (one man, had it very severely), and they all had success. Through chiropractic care and nutritional testing (this was really key), many really felt a big improvement. I'm not saying it's going to work for everyone, just as modern medicine won't...but it did work for, and help many. Just a suggestion!!
P.S. I TOTALLY agree with the probiotics suggestion!!