Chronic diarrhea can be evaluated with a colonoscopy - which can evaluate for colitis, inflammatory bowel disease or possible masses or cancer.
The stool should also be sent for culture and analysis - to exclude infection or malabsorption.
I would also do blood tests to exclude celiac disease.
Regarding the upper GI symptoms, an upper endoscopy can evaluate for GERD, ulcers or inflammation of the esophagus or stomach.
These options can be discussed 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 patients education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
www.kevinmd.com