What Causes Constant Pounding Headache?

Hi, Im male, 5'8", 167 pounds, and i've been healthy all my life. I've had a consistant pounding headache for 7 days now. It hasn't gone away. When i press the soft spot right below the skull a the back of my head, on the left side, the pain gets worse. also, when I move any way, it pounds harder. What can this be?