Feeling tired.

I'm feeling super tired these days. Really, it's so hard to keep my eyes open. I don't even know why, because usually I'm still 'awake' with 8 hours of sleep, but now, I'm feeling super tired with 8 hours of sleep. :/ It's really weird. And the dizziness is coming back, too. It had been gone for a while, but now, every time I stand up, I feel dizzy again. It's actually really annoying. And I have a really bad headache now... I'm not feeling good at all, but I can't stay home tomorrow because I have a test for PE and for geography. And learning for geography isn't really working - everything I've tried to learn for it in the past days, is already gone. I know nothing, no matter how hard I learn. I just keep forgetting everything. Now how am I supposed to get a good grade? I'm so dead...