Puppy Vomiting/Regurgitation?

Since the vet checked for megaesophagus, it probably isn't that, but it could be a congenital condition that often leads to megaesophagus if it isn't corrected called Persistant Right Aortic Arch PRAA). Here's a link with more information: a href="http://www.squidoo.com/Megaesphagus-Dog" rel="nofollow"http://www.squidoo.com/Megaesphagus-Dog/a