Hi good morning since your question is pretty straightforward would like to address is directly. Now after a restoration is done if the patient still complains of pain there can be only two understandable reasons that either the restoration done has not conformed properly with the tooth surface something will call as high point or the next probable reason is the infection in some canal could have progressed to the underlying nerves and blood vessels in root canals.
Next Steps
Plz visit the same dentist with the concern or demand for a pedodontist.
Health Tips
Sometimes what is seen on xray cannot be considered 100% right.