Hello hardhit.......,
it does sound like you might have developed tmj. Since your main pain is headaches, you might be able to stop this from getting any worse by getting a bite splint.
If you are able to find a good tmj bite splint maker/doctor (and they can be dentists, orthodontists, oral surgeons), you will also have a good start at "fixing" the problem. Shop around for a good specialist. If the person starts out by talking about braces and surgery right away, I would run away and try someone else.
A good bite splint is also very important. There are several different kinds and they do serve different purposes. Do some research and go into any appointment educated. Do not get discouraged if the first bite splint needs lots of adjusting or ends up not being the one. Patience can be very important to get that perfect splint.
Don't be surprised if the specialist suggests valium at night for a couple of weeks (or you could ask for it). Take only a low dosage and don't plan on taking it longer than a few weeks. Even a seratonin regulator like prozac might be a good idea. Again, start with a low dose, plan on it taking at least a month before full effects are felt and wean slowly off when you want to stop.
I hope these are helpful suggestions. You really are at a good position to be "cured." there are other suggestions, of course, like moist heat & ice, physical or massage therapy, eat only softer foods, relaxation exercises like yoga, etc. I would skip chiropractics for now.
I hope and pray that you get the help you need. Research, research, research is very important, so get busy. :)
god bless...
Carol