It could be a number of things that can cause the sensitivity but since the timing of the pain occured after the temp crowns were placed, I would suspect that replacing the crown may fix the problem. I would try that first prior to doing anything more extensive. Sometimes just placing the permanent crown can solve the problem.
Best to consult with your dentist to your particular case though.
It can be a wide range of possibilities. It is most likely caused by the gums themselves due to the fact that the root canal was done. This gum irritation can be caused by excess cement, high bite/occlusion, periodontal disease (gum disease), trauma to your gums, it could be referred pain and not actually that tooth but a tooth nearby, etc.
Your dentist would be better able to figure it out.
Will you please share the other possibilities of what could be causing sensitivity?
FYI, I was wearing an old mouth gard which was not fitting well post the proceedures, the dentist did adjust it however I stopped wearing it to test whether that could be causing the sensitivity. I doubt it is the 'main' culprit but I'm having a new one made.
Thanks for sharing your thoughts about vairous causes post crown work and sensitivity.