severe Nausea and Vomiting, when I eat i get sick.

I'm 29 years old and for the last few years ive had severe Nausea and Vomiting. It comes after I eat can be something as simple as crackers. I spend most of my days with headaches because I know when I eat i'm going to get sick. It can sometimes be just upset stomach w/ heartburn or it could be all out rolling explosive vomiting. Usually after i stop vomiting i feel better like the cramping pains are gone. My Doc's done 3 Endoscopies in the last 4 months and has another one scheduled for next month. He's got me a HIDA Scan scheduled for tomorrow. I've got virtually no pain except for cramping in the stomach, feeling like I've had a knife shoved right thru my breastbone and right into my back under my right shoulder. No one in the last few years has been able to figure this out and i'm tired of having nothing to eat. I was told i have severe ulcers and have seen them via the endoscopy but that only counts for why I have heartburn. PLEASE HELP! I'm desperate and want to try something.