Ladies, you were all so right! Thank you for your suggestions... I decided to take two days off from the bike, took a nice walk on one day and forced myself to do nothing the other day. WOW, what a difference it made! When I got back on the bike, my legs felt stronger than ever.
Cunninghamair, I think I was burning out from over doing it. I was told that as a beginner it would be almost impossible to overtrain. Guess not...
Crankin, I hope I'm doing as much as you are at 55. Rock on!
Alpinerabbit, thank you... I never thought about the injury part... So true.
Thanks to everyone. So much good support!