Local Rebel brings up a few good points.
If it persists for two weeks, that's the official amount of time when you're supposed to seek help for it.
As for the question, what do I do? What I do won't work for you, so instead I'll say what would I do if I was you...
Maybe take a day off of work and spend it just relaxing... have a bowl of ice cream with banana sliced up in it. That always helps me out (worked tonight!). Watch daytime talk shows, and laugh at some of the funny situations these people are in... and maybe learn that your life isn't so bad, if you have greater things to worry about than the silly problems they deal with. That just says you have a good quality of life, and have high expectations... and that you're an intelligent person. Good confidence boost.
Rent a few movies you've been meaning to see (not necessarily relaxing ones, just any movie that you think you're going to enjoy). The trick to relaxing is to try and forget you're relaxing... don't punish yourself for doing something unrelaxing. Take it easy and do whatever you like.
One day of that should be enough to make you right as rain. All you have to do is call in sick for a day. (cough cough, i'm so ill, oh my head, cough cough)
Just my own opinion.
Be well, PDV.
"I know it's nice to be known - It caresses your ego - but the society cost is terrible."