Why did I have a traumatic and painful experience during my RCT treatment?

Hi doctor,

I had a root canal and it was a traumatizing experience. My endodontist tried for an hour to give numbness to my tooth. He gave a maximum amount of Novocain and told me that no more can be given after this level. He told me that my pain gets manifested by being tense and you need to go through it for having a treatment. After some time, he proceeded further to finish the procedure. I had pain with tears rolling down my cheeks. It hurt me a lot and I was digging my nails into my arms to distract myself from the pain of my tooth. Now I have huge swollen scratches on my arms. I had pain while doing a root canal. Is this normal to have it? Is it impossible to numb that area? Is it normal to have a huge amount of pain while having root canal treatment? He gave me 20 units of Novocain and told me that no more can be given above this level. He told me that the final result turned out beautifully. But I feel upset and traumatized from this experience due to pain. I am anxious.