Hi, Welcome to health care magic, Persistent diarrhea could be infective (virus,bacteria, parasite) or dysentery or lactose intolerance or irritable bowel syndrome or drug induced etc but it needs further evaluation by various medical tests. You may go for routine blood count,electrolytes and stool examination with ultrasound abdomen and upper gastrointestinal tract endoscopy (if required) as you have already done colonoscopy. Treatment is mainly depend on the underlying cause but you may require antibiotics(ofloxacin with metronidazole) if infective, prebiotics and probiotics,antispasmodics, antacids,antiinflammatories etc. You consult your gastroenterologist who will start treatment after carefully inspecting your reports. Regards,