I had something like that a few years ago. It was just a swollen lymph node. It hurt me a little bit, but not much. Within a few days, and some antibotics, it went away. It could be something else but I don't know.

EDIT: I went to the doctor withing a few days of noticing it. They said that if it is worse enough, then I would have to have surgery to remove it. Hopefully that's not his case. since its been swollen for a couple of weeks.