[billieball]

You actually have a set of sinuses near the back of the head. The pain from these can radiate nearly anywhere on your head. I speak from experience, as I had to have sinus surgery a couple of years ago. Every sinus cavity in my head was hollowed out, bones were broken that honeycombed in-between the cavities, yada, yada. Before the surgery, I would have crazy pains in different places in my skull...even on the front of my face. Now, I wasn't diving then, but the pansinusitis I had at the time meant that every sinus cavity was filled with infected crud. I probably couldn't have gone down 1 meter had I been diving.
Sorry for rambling...just thinking that maybe you could have some sinus issues. If so, they could clear up on their own. If they don't, seeing a doc is the next step.