Sounds like a boil. It's like pimple but much bigger and deeper. Unfortunately, I have quite a bit of experience with those. They are quite painful. Daughter got one on her arm last summer. It was horrible. After many hot compresses it finally started to drain. Then it seemed to heal over. Then it came back bigger than before. Daughter was in a lot of pain and very grumpy. Any touch to it sent her into screams. Finally, we had to take her to the Pediatrician to have it lanced.
Oh boy, that brought out the worst in Daughter. She kept threatening the Dr that she was going to punch him in the face. Now,isn't that lovely??
Anyway, that took care of it and it healed. But, she is left with a scar.
Put hot compresses on it. As hot as he can stand. Don't try to break it open (very tempting). Keep it clean by wiping alcohol around it (very gently).
I don't think it requires the ER (though I know it must really hurt), but making an appointment with a MD might not be a bad idea.
Good luck with the DMV. How frustrating!
