Body Function Fail

Lately my jaw has been going lazy on me when i eat. I'll be mid-chew, and my jaw muscles start getting all kinds of tired, and then finishing the bite becomes this major undertaking. Every chomp stretches out in time like i started eating in slow-motion, taking forever to complete one mastication cycle and move on to the next. I reach up and massage the flagging mandible like a boxing coach rubbing down his prize fighter. I even kind of project a mental pep talk to it: 'Come on, you can do this! You can take that bite of tuna! That shit's practically already chewed for you, quit being such a pussy!' I kind of start bobbing my head a bit, like involving my neck is somehow gonna make the job easier, but it doesn't. It just makes my neck tired too.