Aw I wish I knew what to say. I had a traumatic experience at that age, too. I needed a cavity filled, but the dentist said it wasn't deep enough to need pain relief. Well,it was. He hit a nerve and I started screaming, but he wouldn't stop. My mom was screaming at him and he just kept drilling. The he slipped, I guess because I was screaming, and hit the inside of my mouth with the drill. There was blood everywhere.
I don't have any advice, though. I very rarely went to a dentist after that, only for extreme pains and I cried the whole time. I haven't gone in over 4 years. Poor kid.