I know this is not what you want to hear. But. your dog probably needs more diagnostic testing to determine what is wrong. He may have a congenital anomaly? He may need a surgical procedure? He may need prescription medication and continued care?
Of course this is all speculation. Only a veterinarian that has examined your dog can make a diagnosis and prescribe treatment.
So, I would call the vet (that has examined your dog) leave a message for him to call you back when he has a minute to talk and see what he advises.
PS: His condition could be something simple that will respond to treatment? I would get some answers.
