Pretty much the same thing happened to me after I took Cipro, I developed pseudomembranous colitis/C-Diff Toxin and in addition to taking Vancomycn and I took Culterelle twice a day.Taking it finally helped me get rid of the C Diff Toxin (after 4 months), but doesn't really do anything to help relieve my diarrhea from IBS.If you are looking for another good source of probiotics though, you should also eat yogurt.