Ever since I was a child I used to get abdominal cramps followed by Diarrhea 1-2 times a week and I was never able to find the source of what was causing it and I finally accept the fact that I had IBS. I am now 31 Years old and I found the source to my problem and I no longer have abdominal cramps with Diarrhea it's been a year and it has changed my life. The source of the problem was tap water... Chlorinated water. I stopped drinking tap water and a month later I had no more issues. Please try this and see if you also have chlorine intolerance. Definitely worth trying :)
Chlorinated tap water gives a relative of mine diarrhea, too.