If there's no obvious reason for a black stool (such as food, a supplement, or a medication like Pepto-bismol), it could be time to look for blood in the stool. 1  A variety of medical reasons can cause black stools that are also tarry with a foul smell.
1 Lungs, kidneys or liver. Inflammation may cause pneumonia, bronchitis or other problems in your lungs; may lead to problems with kidney function; and may cause hepatitis or cirrhosis in your liver.  Lymph nodes. A small percentage of people with Sjogren's syndrome develop cancer of the lymph nodes (lymphoma).
SjÃ¶gren's syndrome is an autoimmune disorder in which immune cells attack and destroy the glands that produce tears and saliva. SjÃ¶gren's syndrome is also associated with rheumatic disorders such as rheumatoid arthritis. The hallmark symptoms of the disorder are dry mouth and dry eyes. In addition, Sjogren's syndrome may cause skin, nose, and vaginal dryness, and may affect other organs of the body including the kidneys, blood vessels, lungs, liver, pancreas, and brain. SjÃ¶gren's syndrome affects 1-4 million people in the United States.