Sorry to hear of your headache and pain HN.:(
I find often myself with my shoulders up around my ears! It is just a habitual tension that I carry...like the mouth tension that you mentioned.
Here is the link to the Progressive Muscle Relaxation exercise that is helpful for relieveing tension, and hopefully the symptoms you are experiencing.
Practicing it throughout the day will hopefully re-train your body to release the upper body tension you are holding. :)http://www.stress-relief-exercises.com/progressive_muscle_relaxation.html
Best wishes with this!
"Courage is not the abscence of fear, it is feeling afraid and doing it anyway!"
"Worrying does not empty tomorrow of its troubles...it empties today of its strength."
Corrie Ten Boom
Panic Syndrome recovery due to CBT