Hello! Thank you for the query. Black stools (tarry like) should always be verified with bleeding from upper digestive tract (usually peptic ulcer). This is always urgent situation and should be treated in the hospital. Other possible reason of your symptoms is partial bowels obstruction due to abdominal adhesion (as you have two abdominal surgeries before). This one is also urgent condition. I suggest you to visit ER and have this two mentioned conditions ruled out. Abdominal ultrasound, abdominal X-ray, blood work and upper GI endoscopy (if hemoglobin level will occur low) should be performed. If urgent conditions will be ruled out, you may suffer from intestinal infection. In such case you should keep yourself hydrated, have soft diet for a day or two. You may ask your doctor for medicines like Nifuroxazide and Loperamide. Hope this will help. Regards.