Hi there...it looks like your son could be suffering from acute gastroenteritis. Sometimes even gastritis, gastroesophageal reflux disease, meningitis can cause such symptoms. It will require detailed clinical examination and probably further blood tests. So kindly consult a nearby general physician as soon as possible for further evaluation. Till then you can give him tablet pantoprazole 40mg plus domperidone 30 mg tablets, once daily half hour before food.