What Causes Chronic Diarrhea Inspite Of Taking Pepto Bismol And Probiotic?

I have had the main problem of diarrhea for weeks. I have seen a doctor who ordered a stool test. It was normal that was on May 1. Also saw him again on May 12 still with diarrhea issues. Nothing helped as he told me to try ( which I explained I had taken Pepto Bismol with no help) Amoniam AD. No help. He also told me to take a probiotic ( which I take daily in capsule form or with yogurt). Nothing helps so again another stool test. this time a nurse called and said the stool test was pending but my blood work taken yesterday was normal. Could this because of abdominal pain with diarrhea and some nausea but no vomiting no fever be anything to do with my liver or pancreas?? I am on metformin for diabetes and he mentioned we may need to change that med