Hi thanks for asking question. You history of taken outside food. So here definetly first possibility is food poisoning with bacterial or viral gastroenteritis. Ofloxacin with ornidazole useful to cover causative organisms of food poisoning. Along with it omeprazole also can be taken. Examine your stool as it might reveal parasitic infection like that of ameba egg or giardiasis trophozoites. Drink more water and fruit juice. Avoid excess smoke. Take semisolid diet for few days. Take ORS powder with water to maintain fluid and electrolyte balance. If still cause no clear and condition worsening then endoscopy or ultrasound examination needed. Wish you good health