Hi, having pain in a root canal treated tooth immediately after the procedure is a common behaviour, which ideally should subside in 3-4 days. Your doctor may prescribe some pain killers for the time being. If pain does not subsides then there can be a variety of reasons like 1) filling on top of the tooth being slightly high than other teeth , which can cause more pressure on the particular tooth and may result in pain. 2 ) there can be a gap between the filling and adjacent tooth where food might get stuck and can give rise to pain. 3)there can be some residual infection beneath the tooth which has not healed completely and ia giving you pain . Meet your doctor, I am sure he will be able to help you out with this
Next Steps
get a Fresh radiograph done to check for the root canal treatment , presence of any infection or gap in the fillings .
Health Tips
It can just be a post operative pain and might just heal automatically in few days. Ask your doctor whether you need a cap on this particular tooth or not . generally teeth with large fillings on top post root canal treatment require a crown to protect the remaining tooth structure .