i would take him to the vet immediately i wouldn't wait till he sheds cause the respiratory infection wont cure itself it will just get worse but the spots on his face probably will come off when he sheds. and when you take him to the vet make sure they do a culture to make sure they are going to give him the right antibiotics. i would just tell the breeder that you are going to take him to the vet cause you dont want it to get any worse and maybe he will compensate you for your vet bill since he was going to take the snake back and give you a different one.
I hope everything works out for you and if you get him to the sooner you get him to the vet the better cause if left untreated that RI will get worse and probably spread to your other snakes if you aren't quarantining him. If you dont already have him in Quarantine then you should do that right away.