My knees hurt really bad and I dont work out. I am 22 years old?

I went to Las Vegas last weekend for EDC 2011 and came back mid week. I went to one day of work, came home and that night my knees started hurting in bed. I am been in constant pain every since. It hurts most when I am laying down, hurts when I am sitting, and hurts least when I am standing. Its like this really intense soreness. I don't know what to do. I have been staying off them as much as possible, sleeping lots to let my body heal. I don't know what to do, I am starting to panic. I am to young for this. :(