Hi.
Even after a root canal, pain can still happen because the tissues and ligament around the tooth are still alive and contain nerve endings. Re cleaning or medicines can temporarily irritate these areas, causing pain even when the nerve inside the tooth has been removed.
It is likely temporary post treatment inflammation which should settle gradually.
Next Steps
Give it some time, mostly a week. Then you should be good to go with crowns.
Health Tips
The dentist you are getting the treatment done with is best to take a call when crowns are to be given.