jaw pain

The other day I sat down to eat dinner.  As I was opening my mouth I got an excruciating pain in my left jaw that lasted a few seconds then it would hurt off and on for another couple of seconds then stopped.  About 20 minutes later it began to swell.  The next morning most of the swelling was gone but is still swollen some.  What could have happened......I dont remember a popping just the pain.