could it just be overtraining? maybe you just need to take a few days or (gasp
) even a week off the bike and recharge your inner batteries.
I believe you'll find Several of us here going through one stage or another of the change, I would like to think my bike riding has kept me from killing anyone - yet!
I'm also a runner and have been for over 20 yrs and have just learned to listen to my body: if it tells me I don't wanna do that, I don't. The bike won't go anywhere until you're ready to hop on again!
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"