I own a German Shepherd Collie mix named Sammy and the other day while jogging he sprained his ankle. We took him to the vet and they said everything was fine and it was just a sprain.
He has been lifeless and traumatized. He doesn't do anything, he wont go outside to go to the bathroom (we have to carry him outside) and doesn't even come down from under the bed when we're eating like he usually does. He's been acting really weird and not himself. He wont come down to eat his food or drink.
You need a second opinion on your dogs injury, it sounds MUCH more severe than a sprain! It may take an MRI to find the problem, in the mean time, he should be kept on GROUND LEVEL, no stairs, no excessive activity.