Those can be symptoms of parvo...

It can also be symptoms of food allergies. If you've had your dog on RAW all its life and just switch it to dog food it might really mess it up internally.

But I think your vet really needs to look at it, do blood work, etc. Try to think of anything you've done differently, and tell your vet.

If you're not sure of your vets ability to diagnose, please seek out a second opinion. Not every vet is wonderful.