Lump by ear, painful jaw?

This morning a small lump appeared by my ear, right by the tragus. My jaw has been sore all day and the lump has grown a bit larger by now and is tender but not moveable. I was at the doctor's in the afternoon and he did an xray to make sure there wasn't anything wrong with the joint, but said it looks fine and I probably just overexercised my jaw or something. I'll go back next week but I'm not really satisfied with his answer as it's hurting more and more as the evening carries on... Anybody know what it could be?