Completed the RCT means the dentist had already filled the entire root space and restored the crown with a permanent kind of filling right? Did your dentist mention that?

We won't be able to give you any concrete solution to your problem unless we have the detailed examination of your oral condition. That pain can be due to so many kinds of reason and sometimes even due to tooth/teeth beside it that's carious or having gum problems. It's best to check back with your dentist on this issue.