Most of the time, it's food impacted in your tooth or gums.

Wal Mart carries a Dental Emergency Kit, and in this kit is eugenol, which dentists use for topical numbing.

Put some of that, or clove oil, on the area, clean with (I use the plastic toothpicks I got at walmart) something that you can clean the gums and crevices of the tooth with, then brush the ****ens out of the area, and it may fix the problem.

Arnica Montana 30X is good for pain.

HB