The kind of complaints and symptoms your son has presented with, it looks like to be Acute gastritis. Of course treating physician would have treated him and also advised upon the regular intake of tablets for prevention for further such episodes. Having good and timely diet habits (curtailing on smoking, drinking, carbonated drinks, tea and coffee) shall defineitly help him out. He has to be evaluated and find out exact reason for such vomiting episodes. Upper gastroduodenoscpy shall help.