Hello, Black stools are also called as Malena. The commonest causes are as follows: - Bleeding in the intestinal tract from oral cavity to mid colon as the blood from mid colon usually appears like red stool or altered color as there is no sufficient time for the blood to be transformed into black. - Intake of iron in any form from medicines to diet high in iron contents. Hence, I would advise you the following: - Send the samples of stool for tests including for blood and altered blood also called as occult blood - Ano-proctoscopy and colonoscopy - Upper GI Endoscopy - Capsule colonoscopy if all the above investigations fail to give the cause - CT scan of abdomen Once the cause is found get treated according to the cause found. Have proper follow up for Osteoarthritis and fibromyalgia which indicate that you have problems with anxiety and/or stress. Also consult a Trichologist to take care of hair fall. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. T Chandrakant