Seeing a tmj specialist is advised, if the quality of root canal treatment meets current standard of care.
I am NOT a dentist. But, I had horrible pain once after a dental procedure. I couldn't even open my mouth. To make a long story short, I was finally diagnosed with Complex Regional Pain Syndromd, and after about a week of medication to block the nerve pain, I was cured. The trick was that I found the right dentist/MD, Dr. Piper. He helps people with minor problems like mine, and people with very severe, long-standing problems. I was lucky to only be a few hours drive from him. But, he has many happy patients from all over the world. You can find more about him and his clinic on the internet at pipererc.com
Hope you feel better soon.