I totally understand you! I had the same experience when I was in my late teens. I went to the dentist just for fillings and even though they gave me shots to numb the tooth, I felt a really intense pain and never knew when it would come. So after that I avoided the dentist and now I am paying for it with a ton of things that need fixing. Just this week I went to the dentist for a filling and a build up on a tooth that had been root canaled. Even after 3 shots, which numbed my whole right jaw, I could still feel an awful pain randomly. It was awful and I will have to force myself to go back, I sure don't want to.
I think I might consider sedation dentistry in the future. I have read some posts on this board from people that have had it done and it sounds like the way to go?!
Good luck to you