HI, thanks for using healthcare magic The most common reason for the symptoms mentioned would be an acute/recent onset infection of his gastrointestinal tract.. gastroenteritis. This can be caused by a viral or bacterial infection most commonly. Treatment involves: (1) holding off all solid food till there is a 4 hour window with no symptoms When this 4 hour period occurs then very small amounts of dry food such as biscuits or toast or plain rice , should be used (2)fluids in small amounts. He should use 1 tsp to 1 bs of fluid every 5 mins for 1 hr, if this is tolerated then the amount can be increased. He should use either dilute sport drinks or oral rehydration products (3)probiotics (4)meds such as pepto bismol If the pain is severe or symptoms are worsening, then he should be seen by a doctor I hope this helps