I'm a girl so if I paint my fingernails I'm less likely to bite them.
My brother has the same problem and got some crazy infection in one of his fingers he had to have treated by a doctor. So I know this is a real concern.
If you are having a lot of pain get it checked out in case of infection. Our hands touch all sorts of things through out the day, so that is a real possibility.
I wish I knew how to stop biting my nails and picking at my cuticles. They look so gross and I'm very embarrassed when I have to shake someone's hand.