I ve had diarrhea for more than a week, and it s gotten worse in the past three days. I m passing dark, now gray, foul-smelling and oily looking stools perhaps 8 to 10 times per day. I don t have stomach upset. I often don t have warning. I have Hep C ( asymptomatic ), am on Coumadin (for an implanted aortic valve ), have tried Immodium and Pepto Bismol and nothing seems to affect it. I have not changed my diet, not been on any antibiotics. I have changed nothing.