hi doctor, im asking on behalf of my mum. 2 weeks ago she suffered from feverish symptoms and her stool was black. dark blood. she s since then been hospitalised and had operation for gallstones and infection because one of the stones escaped into another tube which caused the infection. they also tested her upper and lower stomach and everything is fine. she has been discharged a week ago and since she came out of hospital she still feels abit feverish but not as bad. she s done another ct scan and blood test and results came back normal. this morning she has black stool again. what could be the problem and is it something serious?