Doesn't Make Any Sense

I felt pretty good on Friday, but for some reason I felt worse on Saturday and Sunday. Somewhat lightheaded and nauseous all day long. On Saturday I went over to my sister's place and saw her new apartment, and today I had lunch over at my parents' house. Forcing myself to get out helped me feel a little bit better, but I still pretty much feel like crap, which doesn't make any sense to me, seeing as how I felt pretty good on Friday. I'm hoping to go to work tomorrow, but if I feel tomorrow like I felt today, I don't think it's going to happen...