When my bottom teeth hit the back of my crown while biting it hurts. I have had a root canal done on this tooth as well.

Since this just happened after 10-12 years from root canal  you must seek the care of a dentist.  Exam and xrays should reveal the reason for this sudden problem.  It may indicate a new infection, or root problem.  So, again, contact a dentist at once.

Since the tooth/crown has been fine for 10-12 years, this likely indicates that the tooth/root is fractured or that the tooth is reabscessed. See your dentist right away to have xrays done and the tooth evaluated .