Sometimes I feel absolutely nothing

I have periods of time where I am just an empty, nonthinking shell. For some reason, this time around, it coincides with having a feverish cold. The past few days I've felt nothing, no feelings, emotions, drives. No hunger, thirst, just nothing. It's like the dead zone whereby I'm unmoved and unaffected by anything. I have nothing to do or so.
I hate it when it's like this. Don't know when it's going to end.