causes of chronic diarrhea are
1. infection ( bacterial / viral / parasitic )
mostly parasitic infections are cause. stool examination for ova and parasite three times is done to rule out or rule in infection.
inflamamtory bowel syndrome or inflammatory bowel disease. ( colonoscopy can see lesions. if it was normal , i am not worried about this )
microscopic colitis . it is also diagnosed on colonoscopy.
3. malabsorption diarrhea.
stools are abnormally foul smelling in this and there is usually associated weight loss. stool examination for sudan stain or 24 hour fecal fat content is used to diagnose this.
4. hyperthyroidism can give chronic diarrhea. other symptoms are heat intolerance, racing of heart .
I recommend seeing a GI doctor or your primary doctor and get
stool for ova and parastie x 3.
stool for lactoferrin
stool for sudan stain.
TSH if suggested.
I hope this helps.