Pain after root canal

I went to the dentist to get a crown because my premolar was causing constant pain. The dentist gave me injections and I felt a tremendous shock. He did the crown prep , but when the anesthetic wore off I was still in a lot of pain. The next day he did a root canal with more shots, of course. When the anesthetic wore off, it still hurt an incredible amount. I feel pain in my lip, chin, along my jaw, my throat, deep in my ear, behind my ear, all on the side where I got the shots. It's been 17 days now, and I still have to take advil and tylenol to control the pain. It seems to be getting gradually better. I would like to know exactly what has happened to my nerve and how long it will last. I don't feel numbness, just a whole lot of pain.