So much pain

I am in some of the worst pain in my life right now. On January 9th I had a couple of fillings put in my lower left teeth. Well, after the fact they were bothering me a bit. Not to bad but a nuisance none the less. Last Thursday I had a cleaning scheduled which was good because I had been in pain for a few days. The Doc looked at it and said if it did not get better in a couple days I would have to have a root canal. Well, I am having one on Tuesday at 3:00. I have never wanted to go to the Dentist so bad in my life!! I am in so much pain. I have had to deal with a lot of pains on my body but I think this is the WORST! It is constant and piercing! OUCH!