Something wrong or just me?

I've just started feeling very tired and exausted for doing almost nothing. I've been very sleepy lately, going to bed early and waking up very late, & falling asleep everytime I seat or lay down anywhere. I have also lost my appetite, I don't feel the need of eating, even when I try I just can't bring myself to eat whatsover. my body feels extreemly weak, Buh I can't stop drinking whater! What's wrong with me?