my 11 year old son has been nauseated, non-stop, for 2 1/2 weeks. Every time he takes a bite of food it causes him to vomit within 5 - 25 minutes. The vomiting includes a lot of retching. He hasn't eaten in over 2 weeks. I am frustrated with his pediatric gastro doc who doesn't seem to be much help. No fever just nausea and vomiting, and the vomiting is only when he eats. Also, there's no blood in his vomit. I am at a loss. Any suggestions?