Originally Posted by newB

What you are describing sounds like the classic symptoms of an abscess. I had one myself about a month ago, for no apparent reason. At first it felt like there was something under my gumline - I had eaten popcorn the night before and thought maybe it was a corn husk. After a couple days of flossing like a mad-man, I started getting pain from that tooth when I chewed on it. I went to the dentist, but nothing showed up on the x-rays. Still, the dentist gave me a 7 day prescription for Penicillin and referred me to an Endodontist. I never met with the Endodontist, but the Penicillin seems to have done the trick and I haven't had an issue since.

I should add that the dentist was kind of flummoxed that I did not experience sensitivity to heat or cold as that would have clinched his diagnosis.