
Hi Ian,
I would want to know why the wall of his stomach is thickened - there are a number of reasons why this could be the case and personally I'd want the specifics. It may be an oesophogus problem or could be relating to an ongoing and undiagnosed food intolerance, excess acid, ulceration, pancreatitis, Addisons, EPI, IBD, tumour etc
An ultra sound (although more expensive) would have provided more indication of the greater picture, followed if necessary by biopsy of any areas / organs which appear abnormal.
Random, spaced out periods of vomitting and nausea (classically "air licking") with poorly or undigested food after several hours of feeding can be symptoms of several very serious disorders and your vet clearly has moved in the best direction so far - however I'd not want to be complacent and be inclined to press for the next course of action he recommends to commence.
best wishes, Teri :)