tightness/pressure in mouth and jaw

Yes, I get this too, a real feeling of soreness/tightness around my jaw.  It also travels down my neck and into my shoulders.  I think I get it from clenching my teeth when I'm anxious.  I also grind my teeth at night.  I think it is probably anxiety related but you might want to try using a mouthguard at night in case you are grinding your teeth.  I find the more anxious I am and the harder I try NOT to think about it the worse it gets.  Funny that! Try some deep breathing/relaxation exercises when it starts up, and if it still really bugs you go back to your doc and get checked.

I too clench my mouth , sometimes I massage it to relax it.

I used to grind my teeth (in my sleep) when I was under extreme stress but I don't think I do now as my partner hasn't said so??

jaw clenching and tooth grinding are common for anxiety sufferers, can lead to TMJ, details on the net, the sore jaw mucle pain can seem to come from behind the eyes

a beta blocker med may help

a football mouthguard or splint from dentist can help if these problems happen at night

the grinding often causes tooth and filling problems

There's a really good way to get rid of that tightness in your jaw,or wherever there's tension like that. Clench your teeth together as hard as you can and lift the muscles up in your neck,so your basically tightening up your whole jaw (i dont know if everyone can lift the muscles in their neck) hold it for about 5 seconds and then completely let go,you'll feel the tension going away and you'll jaw will feel much lighter and relaxed. It's all a result from tension which is all a result from your posture or not breathing properly,so concentrate on those things too i guess.