Point the snake's face down, (so it cant swallow)

and dip it just barley in some hydro-peroxide

if the snake is rubbing that will help with the redness, as well as keep the rubb from infecting

1/day for a couple days see if that helps.

just my quick opinion

you can pop the mouth open with something and check it out for infections as well

I use a BBQ metal Shiskabab stick for this, because they are thin and slip right into the mouth. Since its metal the teeth dont get caught or break.