I think dogs have a sixth sense about people that is usually right on. I would try a new vet regardless. Did he ever have those kinds of problems with his previous vet? When making an appointment, let the new vet know what has happened over the phone and ask if there's anything you should do before you go in (muzzle?).
When I was young, I admired clever people. Now that I am old, I admire kind people. -Abraham Joshua Heschel, theology professor (1907-1972)