Anxiety
Thanks for the advice everyone! I love taking my dog for walks and I agree that it helps but unfortunately (actually, fortunately) she's very old and I have to limit the lengths of her walks. Great idea though. It will help.
She just lost the sight in one of her eyes and We're taking her in tomorrow morning for an injection that will stop any pain she might be feeling. I just keep telling myself, "You've gotta be really lucky to be really old."