Swelling has gone to his cheek and his mouth, but only on the side of his face where tooth was pulled. what could this be?

Common reaction: The swelling can be a common reaction to having a tooth pulled. If the swelling remains or becomes painful then infection in the socket is a consideration and you should see the dentist. Try homeopathic hypericum. It works wonders for pain and swelling after a tooth is pulled.

Not normal healing: Check with your dentist asap. Sounds like swelling secondary to an infection.