Chris,
With no weakness or pain, I think you're probably doing it subconsciously. In everything I have ever seen or read, weakness or pain proceed significant problems with gait. You need to find something to take your mind off things. You're going to kill yourself with worry (hopefully not literally). The mind is extremely powerful, and when we home in on things we start to notice and exacerbate all different kinds of quirks.
I have always shuffled my feet a little. It used to drive my mom and brother nuts (Especially my mom who hated to replace shoes before the upper part started to give way). For some reason I seem to forget that when scuff my foot on the curb, or bring my foot down "too hard."
I can also remember as a young tyke paying attention to my breathing to the point where I felt like i couldn't do it "automatically" anymore. I would have to just ride it out until I fell asleep, and my frustrated body sent my brain off to worry about dreamland.
I do hope you feel better, and I do hope you get answers to your questions, but anxiety taps into some of our greatest resources: the mind and our "fight or flight" response. The sooner you get a handle on that the better.
Robert