A pinched nerve, called by Chiropractors' a "Subluxation". Okay, so how did that happen. Well its a little more than your tackle football game at your 40th birthday party. This is what and when this usually happens, almost 99% of the time.
Somewhere around your first or second birthday, you fell down and a bone slipped out of place. This put pressure on the spinal nerve just below the bone. This pressure was enough to cause the organ at the end to not function properly.