thank you. you not mention the characters of stool.there are some possibilities like irritable bowel syndrome
or chronic pancreatitis
.to evaluate the chronic diarrhoea with vague abdominal pain
, thorough check up is needed.you could not ignore coeliac disease.some inv. as upper GIT endoscopy with duodenal biopsy,s.TTG and antiendomyseal antibody(coeliac disease),stool exam(fat malabsorption),plain abd.x-ray,usg and other imaging of abd.(ch.pancreatitis) is needed.so you should contact with a gastroenterologist.