It happens once or twice a month for about three years now. Recently it happened twice in one week which has never happened to me before. It lasts 10-20 seconds and occurs in the same spot every time. Left side of my head a little behind and above the left ear. If it means anything I have had daily headaches ever since I can remember. Mostly very minor annoyances. I thought it was normal to have some sort of head pain at all times up until recently.