You done wore your body plumb out!
It even happens to 25 year-olds.
In training, rest is your best friend. Overtraining Syndrome is a real phenomena. You may not have classic overtraining, but you may be headed that way.
Check out this article.
http://www.rice.edu/~jenky/sports/overtraining.html
"Physiologic improvement in sports only occurs during the rest period following hard training."