Minniea,
I too have an ache in the same place. And yes you are right it is the joint (at least mine is) The pain comes and goes and also is strong when I try and chew on that side. But, I also have trismus from the radiation.
Not sure at this time what can be done, we are waiting for some other things to get better before I do the oral surgeon route. Hope it helps to know that it could be the joint. But as with all our aches and pains. If they persist please mention them to your doctor.
Take care,
Dinah