and passing black tarry stool are the symptoms of gastrointestinal bleeding
. and common causes of bleeding are acid peptic diseases, gastric ulcers
, gastric erosions and bleeding from lower GI tarct. since you have undergone upeer GI ENDOSCOPY (which is normal), its better to under go colonoscopy to rule out lower GI bledding. my advice is to consult gastroenterologist
for further management.
get well soon.