Gastroenteritis can be produced from
viral,bacterial and parasitic infections, contaminated food or water or change
in bacteria that normally live
in the intestinal tract.Chest pain that you are having is due to radiation of pain.
Take adequate fluids throughout the day. The BRAT diet (ie, bananas, rice, applesauce, toast) or soft easily digestible semisolid diet can also be taken.You also need a course of antibiotics like ciprofloxacin or metronidazole.
Hope it helps.