Did you have the same pain after root canal or the pain started after placing the crown. If you had pain after root canal but before crown placement, then it might be indication that infection has not completely healed. In some cases with infected tooth, after root canal it is left to heal for 4-5 days and then crown procedure is followed (especially when the underlying tooth has infection in and around the tooth and gums)
But as you mentioned, after crown placement you are unable to chew which does indicate that you might have high point or after the crown are placed your all teeth are not touching but the crowned tooth is touching first when you bite from both side back tooth.
Next Steps
in both condition, nothing to worry.
go back to your dentist, they will check if any of the issue is present. they might take an radiograph to check how your root canalled tooth is doing. your condition is treatable.
Health Tips
until you go back to your dentist, avoid eating anything hard from that side. if unable to go immediately, have a painkiller today. do not delay going back to dentist, as the pain keep on increasing if you ignore it