For two years i have been experiencing bouts of diarrhea lasting 3-5 days twice a month. i now have had diarrhea for 10 days, black, and fatigue?

C MD: If taking pepto bismol (bismuth subsalicylate) to rx diarrhea, it may cause black stool, iron pills also. If not, black stool is from blood in the gut, until proven otherwise- a big deal. See md now. That much diarrhea can be from infection, parasites, inflammation, e.g. Ulcerative colitis or crohn's disease, less likely other bad stuff. Fatigue can be from anemia, perhaps due to chronic, and now acute bleeding.

See doctor: May have slow GI bleed (esophagus/stomach/ small intestine) which is digested & thus shows as black stool/diarrhea. Fatigue may be due to chronic blood loss. See pcp or GI specialist asap to find out. May need egd to determine site of bleeding. Avoid alcohol & nsaids if possible.