Shefly, are you suffering from any other symptoms of overtraining, e.g., do you feel depressed, have you gotten sick lately or more often than usual, are you having trouble staying asleep through the night, is your resting heart rate higher than normal, is your heartrate during exercise higher or lower than normal, do your legs feel tired when you're on the bike, do you do anything exercise-wise that's off the bike?
If the answer to any or all of these questions is yes, then I'd suggest, as C-Cain has that you take a bit of a break and/or rethink your training plan. You may be overtrained or underrecovered.
Good luck!
Kate
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher