Just a little note, research has shown that it is actually NOT good for us to exercise when we are sick. The body is already working overtime to fight off infection (whether it be viral or bacterial) and to add the extra tax on the circulatory, respiratory, and immune system when it is already taxed can prolong illness. I have read this on webmd and on another site that I won't mention because I can't remember the address right now Memory is a fickle, fickle thing.
I think you should REST and RECOVER.
I think the hardest part of training is knowing when to stay home and stay put and then making myself do just that.
Whether it is overtraining or something viral, the answer is the same.
Chick flick, pjs, soup, rest.

Good luck. Sorry you feel crummy!