I've been very tired lately and had random stomach pains just went to the bathroom and it was black slimey mess should i be worried ?

Tarry black stool: Is suggestive of bleeding in the upper GI tract (esophagus/stomach/small intestine) & should be checked out asap. Other causes of black stools are frequent laxative use, iron supplements, meds like pepto bismol (bismuth subsalicylate) that contain bismuth. See pcp for history & exam. Blood tests can show if anemic; endoscopy can determine of GI bleeding. Good luck.