Clove oil. You can get it in a tiny vial at the chemist. You pick off small bits of cotton, roll them into little balls, and dip into the clove oil. Wring out most of it against the side of the bottle, then place directly on the site of pain and bite.
In your case you might want to make strips of cotton or something.
It tastes absolutely horrible and will make your whole mouth numb, but it is antiseptic and will give you enough relief to sleep.