Thanks for asking the query,
After a sucessful Root canal Treatment the canals are completely removed devatilised and disinfected so there are no chances of pain .
Pain can be due incompletely done procedure , re-infection of the canal, any unexplored canal left out accidentally , food lodgement between the cap and the tooth if the tooth are capped .
Take an x-ray of the tooth this will give the complete periapical condition of the tooth or any left over pulp tissue .
Get complete mouth scaling and polishing done .
Take complete course of antibiotic and analgesic
Maintain a good oral hygiene .
mouthwash gargles twice daily.
Hope this helps out.