I would list the ingredients for both the vet food and the orijen and look for common culprits and then try to find a food that eliminates them. I have tried the orijen fish and both dogs have done very well with it although I have added a bit of pumpkin for some extra fiber.
"Never doubt that a small, group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has." - Margaret Mead