Persistant Dirrhea Or Frequent Stool Movements Generally A Couple Hrs

persistant dirrhea or frequent stool movements generally a couple hrs after eating. diabetic type one. had colonitis in past and similar . for over a month now. no cramping vomiting or nausea just frequently. not always loose stools just frequent. tried cipro and flagyl but made stomach upset. doc is trying doxy and another med. wandering what is going on.