MM - keep a journal of your symptoms. If you have *anything* else: specific soreness, headaches, cold, hot, achey, lack of motivation, dizziness, or anything else, you want to try to find the pattern.

I agree with Knot that you may not be eating enough while riding, and may want to try that. No matter what your situation is, starving yourself is not healthy, and refuelling during or after a ride is healthy.

If you have other symptoms, and you can see when they happen, if you can't change this pattern, you may want to see a doctor to ensure there isn't anything in that sturdy body that's going awry. (I thought I was fit, healthy and indestructable until now, you never can be sure)

Keep riding, though, and keep enjoying!

Hugs and butterflies,
~T~