There can be several causes of your symptoms. For the diarrhea, you may want to ensure it isn't anything
infectiousInfectious endocarditis
Infectious mononucleosis
Infectious mononucleosis #3 - sending it out for ova, parasites, bacteria and white cells would be the first step. If the diarrhea continues, then a lower endoscopy - colonoscopy or flexible sigmoidoscopy - should be considered. Irritable bowel syndrome as well as inflammatory bowel disease are among the chronic causes.
Regarding the stomach pain, this needs to be investigated as well - especially since you have black stools that may be suggestive of bleeding. Ulcers and inflammation needs to be ruled out. An upper endoscopy would be a reasonable test to get.
You may want to discuss these options with your personal physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
Medical Weblog:
kevinmd_b