Pain twinges in head, always in the same place. help?!?

one day, about 2 months ago, I was blow drying my hair. I bent over upside down and a painful twinge shot up the inside of my head. I've continued to get those twinges from time to time, usually when I'm bending down. I get this pressure feeling and then the twinging pain that lasts only a couple seconds, always in the same spot. The only medications I'm taking is Allegra for allergies. Anybody know what this could be or have had the same thing? I'm 20 yrs old btw.