Hi. Thanks for your query. Noted the history and understood your concerns. Stool appearing dark and strange even once can be call for something serious within the gastrointestinal tract. Yes, you are correct, this can be due to intestinal bleeding hence needs the following: Consult a Gastroenterologist. Get the stool tests done for three consecutive days particularly for occult blood. Upper GI endoscopy and colonoscopy is the rule . Contrast enhanced CT scan of the abdomen is a must. Capsule endoscopy helps for the small intestine. Once the cause is found get an appropriate treatment. If there an infection, get a course of an antibiotic and metronidazole with probiotics.