It's probably due to stress. Sometimes I feel stressed I feel a tension in my jaw and it clicks, so what I do to calm myself is hum a tune in my head. I used to just take pain killers too.
Well I am trying to tranfer unis and it is taking its toll on me.

What position to you most often fall asleep in? Depending upon how the weight is distrubuted around your jaw and face, this may be something to take into account.
Usually on my right hand side.

stop eating rusty metal and get a tetanus shot.
What