Pain And Irritation Behind Ears. Why Is There Pus? Is It Yeast?

Hello my name is Robert and my son Shaun has a skin irritation behind both of his ears since birth. Within the last year it has because increasingly more dry skin looking . The past few days it has started to become what looks to be pusing and become to have yellow flakes of skin that peel off. Sometimes it dries out and sometimes it s very wet looking behind his ears even on the hottest days. He has no other symptoms . No fever , caugh, no rash elsewhere, eats great and drinks liquids fine. It looks like a nasty case of cradle cap, just behind his ears . Someone told me possibly yeast but Im not sure . He is going to the doctors but I just wanted to ask