Far be it from to be a pro, but Dog fancy mag had an article similar to this-it had to do with the esophogus tube being narrow so once food goes down it comes right back up-like acid reflux. The dog in the article had an endoscopy (tube down throat, like us!)as Xrays didn't show it. If I recall, it was a simple procedure (well, no surgeury is simple) to stretch it open and the dog was fine. Poor thing, good luck. Definitely suggest this or get a 2nd opinion. Anything is worth a try!