Red Eared Slider Infection

Question
My slider ride side of his face is swollen and bright red. Is that a ear infection?  What treatment can I do?  Is he in pain?  What causes this?

Answer
Swollen and bright red is pretty much a vet call. It is almost certainly an infection- but not one of the problems we usually work with people on to treat at home.

I really dislike not being able to offer you more help, but this is really outside my expertise.