Cycle info: Started my 5th week of Test-e today, 500mg/Week

About a week and a half ago, I came down with a nice little virus that was going around (cold build up in the lungs, cou***ng, sinus deal). I finally got over it and started feeling a TON better. This past Thursday or Friday I felt I was getting close to 100% again.

I wake up this morning feeling blasted, totally exausted and this is after 8.5 hours of good sleep. I took a half hour nap and worked out tonight. My intensity felt pretty good, I was able to focus and really pound out a good chest day.

Fast-forward an hour, and again Im feeling worn down. No energy, joints and muscles are sore, etc.

PS: On a side note, ever since I got sick, my libido took a slight hit, as well as my ability to stay 'up' when I do get aroused.

Am I getting sick all over again or whats going on? Is the libido drop, all the tiredness, etc. a sign of me shutting down?