After trying the FODmap diet, etc, other recommendations--none of which worked, I took my daughter's advice and ate absolutely NOTHING that had white flour in it... this doesn't mean just 'bread or pastries'...it means foods that the stick into their products like canned soups...all of Campbells and local story brands... It is amazing how often white flour is stuck into prepared foods... it took several weeks and all my ibs problems started to completely disappear...This means you eat fruit, meat, and vegetables...period... (so you don't starve! ) This WAS VERY DIFFICULT for me...but the ibs had to be overcome.
I stayed on this strict diet for a year...then gradually ate a few bites of this and that and it didn't bother me... I still avoid foods with white flour for the most part... and unfortunately 'organic' or 'whole wheat' is NOT acceptable....basically its ALL flours except for quinoa... Many people try this for a few days and say 'it doesn't work' because the comfort food drawing power wins out...you have to STAY with it for weeks....if after 2 months your ibs (diarrhea) is just as bad then maybe it isn't for you. Anyway, good luck!