Hi
I have had a locked jaw for the last 3 days. I can only open my mouth about an inch - and when I eat anything it hurts. I looked up lock jaw on the internet and apparently it's a proper condition called 'Trismus'. There is a disc at the hinge of the jaw joint that can bet out of line - like something getting stuck in the hinge of a door preventing it from opening and closing properly. You have to go to see a dentist or your GP for muscle relaxants or a tooth shield type thing or for 'pivotal splints' fixed by the dentist. In the meantime, you are supposed to use ice for 10 mins, stretch jaw, then hot compress for 10 mins, and stretch jaw again.
Hope this helps everyone with a locked jaw. I'm off now to suck some grapes and find some ice!