I have two back molars, side by side with root canals and porcelain crown. After having the first crown around 3 years ago, the very back tooth crowned. Unable to eat on that side without pain, 6 months later I had root canal. My thought were that due to an ill fitting temporary crown that had to be reseated several times along with continued biting down as hard as you can with cotton rolls in between, it caused undue nerve damage. 2nd tooth root canal completed with crown 4 weeks ago. Tonight sharp, shooting pain at times, now with continued light trobbing. I cannot determine for sue, which tooth. I am leaning to the older root canal tooth with pain noted at distal, low gum line.