I have not seen anyone mention the possibility of caffiene withdrawal. I'll touch on that later.
Talk to your doctor before you try any of these things after #1 - because I don't know your medical conditions.
1) Drink more water.
2) Take a children's dose of allergy medicines, and see if it helps. If it does, try adult doses.
3) Clean out your ears with very warm, but not hot water. Some folks can build up heavy wax deposits without ever realizing it, and it will eventually cause headaches. Do NOT use cotton swabs unless you have a deaf wish. (pun intended) Basically, a steady, weak stream of very warm water in the ear will melt the wax and float it out of the ear channel.
4) If you have recently stopped drinking caffiene, start drinking caffiene, and wean yourself off it slowly. Caffiene withdrawals vary in intensity based on how heavy a user you were. Caffiene expands blood vessels. Go off caffiene, and your blood vessels shrink, reducing bloodflow, which can generate a LOT of pain.
5) An asprin a day will help thin your blood, which can help blood flow, not to mention simply reducing pain.
6) Soy based Lecethin will help clear your arteries of deposits by pumping up your HDL levels.
There are other possibilities, from pinched nerves to cancer, to all kinds of things inbetween, but those sorts of things need to be identified by doctors, not some sort of internet kook.