I chipped a small piece off a filling (no pain) and my dentist said it needed to be replaced with a crown. I was in extreme pain after the crown, in my jaw, so they decided I needed a root canal. Fine, I had that too. It's now 3 months later and my jaw still hurts. I've been back to my dentist many times, had height adjusted, taken antibiotics, seen another endodontist, and no one can figure out why my jaw still hurts. I keep thinking something happened during the crown prep, it was definitely something they did that resulted in the pain as I was in no pain at all before I went in (just needed the chipped filling fixed!) I don't know if they won't admit they did something wrong or if they honestly don't know why it still hurts. Any ideas?

It is possible the tooth sustained a fracture below the gum line, which is very hard to see. If it is fractured, usually extraction is the solution with an implant to replace it. I would suggest going to a new Dentist, and ask them to look for any fractures below the gum line.

Reference (http://www.healthboards.com/boards/dental-health/886909-pain-6-months-after-root-canal-30-a.html)