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).
Other symptoms include vaginal dryness, chronic bronchitis, fatigue and joint pain. It can also cause damage to your thyroid, kidneys, liver, lungs, skin, blood vessels and peripheral nervous system. The symptomâs effects can range anywhere from mild discomfort to severe debilitation. Diagnosing Sjogrenâs Syndrome.