Good morning Mr. lybrate-user
Thanks for the query
As per your query you are having pain in recently RCT treated teeth
Reasons for pain in this teeth can be many.
Most common reading is There might be some necessary canal (Extra canal) I'm the tooth
which need to be addressed.
It's always recommended to go with crown/Cap after RCT if not chances of fracture of tooth increases. If you have not followed this the might be some fracture in the tooth which might be troubling you.
Other option is sometime residual infection
remains which compromised the RCT treatment and leads to post obturation Pain.
Do a course of Antibiotics
killer under your Dentist
Guidance. Or you can go for RE RCT of the Tooth.