Have you ever had an agonizing spot between your shoulders in your neck; a headache coming from seemingly nowhere? You try to rub it out, but to no good. You might have a friend or spouse push on the "knot" between your shoulders, or rub your forehead... but nothing happens. It might feel good for the moment, but there is no or very little relief.
The reason is that your discomfort or pain is not coming from the area you are rubbing. It's coming from a distance place elsewhere in the body and what you feel is referred pain from a trigger point.