Thanks for the query to H.C.M. Forum.
Since you are having many symptoms , but may be the root cause of these symptoms tension ( stress , as you himself admitted).
Dark color stool may be due to upper abdominal disease or due to iron related food.
Fresh red color stool may due to disease in lower abdomen as in large intestine or rectum
Since you are an over weight person , so fresh blood may be due to hemorrhoids .
Low temperature of body in your case may be due to anemia
or tension. Consult a gastroenterologist
and get his opinion as both endoscopy
will find out the cause.