Hi. Thanks for your query. Noted the history and understood the concerns. Soft and black stool is indicative of excessive iron in stool, the blood being the most common cause and you have not taken any iron supplements. Gastric Bypass can have stomal ulcer that usually is the commonest cause of bleeding and thus the stool appears black. Gall bladder removal has usually no connection for GI bleed. I would advise you the following: First of all get a confirmed diagnosis by stool tests for three day. Upper GI Endoscopy can get us the most probable diagnosis. Also get blood tested for Hemoglobin and any deficiencies. Once diagnosed, get proper management as per the cause found. Go for soft bland, small frequent diet. No smoking, no alcohol.