Pancreatitis is a definite possibility. But they say you don't have that? Anything show up in your endoscopy? like Gastritis or ulcer? These too can give you killer abdominal pain and vomitting. When one doctor can't help you, its time to find another. Maybe go to ratemd.com and find the best internalist, gastro, and whichever dr specializes in the pancreas, and go see them. And if it is your pancreas, they can remove it. it really *****, and it will mess with your immune system, and youll have to take medication the rest of your life, but maybe it would be worth looking in to. If it is in fact the pancreas causing all your problems.
Have you been checked for autoimmune pancreatic issues?