This happens to me too, but I think it's IBS. One day I won't have any BMs at all, and then two days later I'll have 5. And yes, I keep a food diary and know which foods bother me. But things are just irregular.
Female, Age 20 (formerly ComedyDork)
9 Asacol, Rowasa, 1000 mg Canasa, Proctofoam, Rifaximin 2/day
Digestive Advantage (Crohn's & Colitis), 1 Florastor, 50 mg 6MP, 1 Primadophilus reuteri, Remicade (6 infusions), 2.4 g Lialda, Forvia, 6 Colazal, 1 Anucort, Culturelle, Fish Oil, Calcium/Vit D supplement, 20 mg Prozac, VSL #3