I would suggest you to take your son to a doctor immediately. It could be anything from food poisoning or something much more serious.
Vomiting can pose the problem of dehydration so make sure that he is kept hydrated. I'm not sure how old your son is, but this will surely keep him hydrated. Give him an electrolyte solution or a simple ORT you can prepare at home with 1 glass water containing a pinch of salt and 1 teaspoon sugar dissolved in it. Let him sip on it from time to time. If he also has severe abdominal pain there could be a serious intestinal problem. Stop all solid food and milk based foods. Give him liquids (excluding milk) until his condition is restored.
answered by P P