<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have some leg swelling and have been experiencing black, tarry stools. What might be causing this?  <response>: It sounds like you may have a fracture of the patella which can cause inflammation and fluid buildup in the leg, leading to swelling. The melena could be a result of internal bleeding caused by the fracture. I would recommend you come into the office for an evaluation and possible x-ray. 