My son has been having bad stomach craps and diarrhea. No burning sensation or anything . He says it started Monday morning then stopped yesterday and then today he had bad cramps and was on the toilet for an hour. Now it's been coming and goingand the last 3 times he's been to the bathroom it's just been blood. Could it be a bleeding ulcer? If not, then what could we be dealing with and what do you advise?