I had that two weeks ago. Enjoyed a week of good health after it passed and then....BAM....got nailed with a flu. Lots of NyQuil and sleep...that's the only thing that gets you over it quicker (the tons of sleep, of course...the NyQuil is just to facilitate that sleep).
Man, seriously, its coming and going with me. One day good, the next I am out. Today I might just be OK, but yesterday was horrible, and I worked that way. Its demotivating.