Apologies for what seems like a very lame post, given some other posts on here!
I got what I assume was a mild flu strain back on the 2nd march, it floored me with shivers and sweats, whole body aches, headache, a horrible amount of brownish gunk in my lungs (it went straight for my chest) and the most knackering fatigue I've had since forever. DH says I wasn't hot 
(our thermometer was broken, though we've since bought another) but the shivers and shakes were very real.
It ran its course within about a week (DS1 got it, at least I assume it's the same thing, because it's a bit different with him, and he WAS hot - over 40) and I'm still in bed. 
I mean, I can get up and walk about, I even went out for a brief coffee on Mother's Day, but if I go outside, or attempt to be upright and functioning in the house for more than a couple of hours, it completely wipes me out and I go back to bed. I'm very lucky in that I'm a SAHM, and DH is on strike (lecturer) so although we're going to be skint, he's been around to look after me/get the DC to school etc.
I just haven't experienced post-viral fatigue like this. Is this just what happens as you get older? (44) I'm sitting on the sofa and feel dizzy sitting still. I spent most of today in bed dozing and will head back up there after some supper.