I would suggest you explore the concept of Internal Cleansing or detoxficiation of the intestines (small and large). This is not really recognized by western medicine but it is a core concept of natural medicine.
I have had IBS diarrhea around 2004 to 2005 and then it became IBS constipation up till last year when I resolved to do cleansing. I tried psylium fiber, Colonix, colon Hydrotherapy, etc. nothing worked.
I then went on a wheat-free, meat-free, sugar-free, soda-free diet consisting of mainly fruits for breakfast, brown rice and veges/fish for lunch, and same thing for dinner. Also switched to alkaline water instead of regular mineral water. I was pretty regular by my 3rd month. But I had this heavy full feeling in my abdomen that would not go away.
Last month I went to a chinese doctor and asked that he prepare a medicinal cocktail that would detox my guts. THe results have been very encouraging. THe heavy feeling is about 80% gone. I don't feel too bloated right after eating. My congested sinus is about 70% decongested. I think more clearly. On somedays my energy level is really high - those days are quite rare. I am 32 years old, male, asian.