Thanks for the answer. We are doing the trial with the acid reducer right now. I'm very mentally stuck on thinking this is an ulcer, and I'm pretty sure the vet thinks I'm an idiot (she is probably right). I'm just trying to get an idea of where to go next as far as diagnosis. The vet mentioned both ultrasound and x-rays, but didn't say anything about scoping, so I wasn't sure if that is even a dog thing. And since I'm oh so certain it is an ulcer, an x-ray sounds like the wrong answer all around. I'm not even sure if an ultrasound would show something like that.
Hopefully the meds will just fix everything; if not, I've got another appointment for him in a few weeks for his titers and rabies, so I guess we go from there.
Nine years of stomach issues with Tristan, and now Gusto. Thank heavens I have Meg, my dog with the iron stomach.