Rehoming a dog

Have you reached out to his breeder? Most responsible breeders will take back any dog they've bred for any reason (some even require it in their puppy contracts, so double check that if you signed one), or at will least help you rehome through their network of prospective puppy buyers - many people would jump at the chance for a dog that's past the worst of potty training and not sleeping through the night, haha. Definitely would be my first step if I were in your situation!

Yes, please contact your breeder. An ethical breeder has it stipulated in their contract that the dog must return to them if the owner can't take care of it for any reason.

A dog sired by two champions has some value if still intact. Contact your breeder.

Yes, contact the breeder. It's probably in the contract you signed when you bought him that he be returned to the breeder if you can't keep him.