I got one tooth root canaled and crowned almost five years ago. now, i have pain in it, like it has pus. what should i do?

See a dentist: Please see a dentist if you have dental pain and pus. These are symptoms of an infection, which should be further evaluated and treated.

Dentist as soon as : Possible. You may have developed an abssess and this can be a fairly serious infection if you do not get it treated. Any sign of pus should be assessed as soon as possible. If you start having any systemic signs, fever, chills, confusion, consider seeing a physician sooner. Best of luck and hope it all turns out okay!

Root canal hurts: It also can be the roots are not perfectly clean (which can sometimes be difficult). Have your dentist take an x-ray to see if there is an abscess. It can be fractured under the crown as well. Do warm salt rinse for now and go asap to the dentist.

See dentist soon: It sounds like the root canal is failing or your tooth has cracked. Consider seeing a root canal specialist in order to see if the tooth can be saved. If it does need to be removed consider replacing it with an implant, there are considerations you would want to discus with your restorative dentist first. Prognosis on keeping your tooth is not very good regardless of the origin of the infection.