Hi thanks for contacting health care magic..... Here according to history it seems to be food poisoning like bacterial gastroenteritis.... Rather then doxycycline I would prefer to use ciprofloxacin 500 mg tablet daily for 5 days..... Meanwhile avoid outside foods and junk foods ....for few days.... Fruit juice helpful.... Green leafy veg more. Soft and bland diet taken.... Heavy fatty meal restricted. Cooked oatmeal good for soothing. Avoid smoking and alcohol.... Meanwhile maintain hydration..... If no benefit then stool examination done , if show egg of ameba use metronidazole.... If shoe egg of hookworm or round worm then albendazole given..... Hope your concern solved. Dr.Parth