Child vomiting

[user1494838646]

My little boy who is five in August vomits frequently at least once a week sometimes more always after food , we have been to the Drs and they tested him for h pylori bug (awaiting results) they also think it could be some sort of dairy intolerance im not convinced as he probably has dairy most days and isn't sick every day , it's getting to the point now when we go out he won't eat and panics because he has been sick a few times in restaurants anyone else's children had similar issues he is always fine before and after being sick
But it's usually within minutes of eating I'm lost at what could be causing it thank you