Burning, slightly painful sensation in head.?

Alright, there's a burning, slightly painful sensation in the lower-left corner of my head. It's been happening for a couple of hours, but now it's gotten worse. It's bugging me, and I'd like to know if you guys have any idea what this might be. As a side note if it helps, I've been having headaches for the past few weeks (sinus and tension) and have been staying up pretty late.