My dentist gave me two shots of novicane and began to drill. he said that if i feel any pain to let him know. i then felt a surge of pain go right through my head. he had hit a nerve. he gave me another shot and proceeded on. is it normal to hit a nerve while drilling? i just find it odd because now i am in excruciating pain and need a root canal. and also my tooth is dead. could this be a result from when my dentist hit the nerve ?