Hello, Diarrhea for four months needs a proper clinical evaluation and examination by a gastroenterologist preferably and investigations to support the clinical diagnosis. -Tests of stool for three days. -Tests of blood for thyroid and liver functions. -CT scan of the abdomen. -Colonoscopy and biopsy. -A course of an antibiotic active against intestinal infection. -Probiotics in capsule and food form such as yogurt, Banana, activated charcoal. -Avoid foods and beverages that instigate or enhance the problems. -All these will lead to a proper diagnosis and help you get a specific treatment. If all the investigations are normal then the obvious cause may be IBS that is irritable bowel syndrome. hence reduce the stress and anxiety as these being the commonest cause and avoid foods that increase the problems. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. T Chandrakant