I have TMJ syndrom and my jaw will at times click and at other times will not. Sometimes it clicks really loud!
It would be very interesting to see if this could be linked to Crohn's--it is inflammation so I would not be surprised.
My jaw has never locked up on me, but it does give me bad headaches from time to time--usually it depends on how much stress I have and how much grinding and clenching I do.
I see my GI next week...I might just ask if TMJ CAN be related to having Crohn's.
Good luck with your jaw! TMJ problems are NOT fun!