I have had this symptom for years now (I am 34 years old). It almost always happens when I am resting, not active. Sometimes it wakes me from sleep; a powerful ache in my jaw, down my neck, and into my chest. It is VERY frightning, and will last for 5-10 minutes if I don't drink water.I saw a cardiologist years ago and they found nothing wrong. I have no health insurance now, so I have not been back for further checks. However, I have found that drinking a few swallows of water, will make the pain go away within seconds. See if this works for you, at least until you figure out the cause.   I have no idea what this condition could be. I eat healthy and I excersise regularly. I have always been physically fit. I think that stress may be one of the triggers, but this is hard to confirm. Stress comes and goes, and there's no way to measure it. I have simply learned to live with it for almost 10 years now.