I've gargled with hydrogen peroxide and water (half and half) and it definitely helps. A good friend, who sings semi-professionally, swears by half peroxide and half Listerene. (I think he's a little "touched" in the head, but he's a MUCH better singer than I am).
If you don't have any hydrogen peroxide (cheap at any drug store), you can try the Listerene "Pre-Brush Whitening Rinse". It's got the peroxide in it and you can gargle with it.
Wait a little while after gargling with this, then gargle with warm, salty water - about 2-3 teaspoons for 8 ounces of warm water. It'll help soothe the throat.
Good luck to you!