Mike - I fought achilles pain for 2 years, probably because I would not stop running.
I finished a couple 50 milers and could not walk for 2 days after, but a week later could run again.
also, if you can stretch your ""upper"" calf muscle by standing and leaning against the wall. often calf tension will lead to Achilles issues, and this stretch has helped me out a lot, the pain was in my heal but working the calf muscle with stretching and massage is what helped the most.
if you exercise, warm up well, and don't sprint for a while.
my guess is that nice Georgia weather got you all exited about running and you pushed the pace a bit, much different than snow shoeing.
... this is assuming its just a tendon problem and not a stress fracture.