The pain usually comes from the position of the jaw, and the muscles being in a tight position changing how the
jaw and mouth anatomy sits, causing discomfort
and occludes blood vessels. Like the song says, the ___ bone is connected to the ____ bone... we're all connected and when one thing is tight, usually the next thing down the line is tight.
Go for a massage, it will do you good and take out any upper back/neck/shoulder tention you may have.