Thank you to those who replied. She seems to be doing better today, not worse, but not totally better. We are going to not let her 'run' after Rita when we play fetch with Rita, she doesn't need to be 'running' at her old age!
Lizbud, it could very well be the colder weather! Although here in CA, it's definitely cooled down, but not quite cold yet. But it could very well be.
Thanks again guys, keep them coming.