Well I started getting IBS-D about 3 years ago and got an endoscopy and a colonoscopy. What they found was that I had an ulcer. Nothing else. Well I was chewing tabacco at the time. I quit thinking that would stop the D. It didn't. The Doc put me on Prilosec for 2 years. That healed the ulcer but the whole time I had D, side effect from the Prilosec. As soon as I quit the meds I was better. In the end I think that the chewing started the ulcer which triggered D. And the med that I used to heal the ulcer caused more D. It made it so when I had acidic foods, such as, tomato sauce and orange juice it triggered D. The lower amount of stomach acids made it hard to digest more complex foods. Also what really helped with the D was intense exercise once a day.I really hopes this will help someone. I know the suffering that you go through.