Cavities and needle phobia?

i am 13 years old and i have the worst needle phobia EVER right before i get a shot or whatever i feel like i am gonna die, i freak out. and after i usually p out, or get really close. i went in to get 4 cavities filled and i had valium and gas and when they said just a little pinch i snapped my jaws shut and i wouldnt open up and so after an hour of trying to coax me we left and i still had 4 cavities. That was 5 months ago and my mom wont let me go to hollyball if i dont get them filled. any tims? could i take a sleeping pill before, if so what pill over the counter will TOTALLY KNOCK ME OUT? and what other drugs could i take before that wouldnt interfere with the nocacane? Please help my teeth are starting to hurt.