Anyone have intense pain during root c?

I had a toothache last week and say a dentist on 12/1. She started the root c and said to come back in a week to finish (today). After the first appointment, she prescribed me anitbiotcs and pain reliever. She numbed me up today, and as she began to work, I kept feeling sharp pain. She would stop and numb me up more. After about an hour and 8 injections, I was fed up. I told her to stop and told her I could not finish because of the pain. I've had 5 other root cs in the past and they were almost painless. Has anyone even had this kind of pain during a root c? What should I do now? I need to have the root c finished, but now I am totally scared of the pain.