What Causes Sudden Sharp Head Pain Behind The Right Ear?

can anyone give me a clue as to why I am suffering from sudden sharp head pain above and behind my right ear? It has only occurred in the last couple of days. The pain is coming often, sometimes several times a minute, its very sharp, makes me wince and catch my breath and is then gone. There is no warning and is worrying me. The area is beginning to feel bruised, without being poked about.