It is not common for shingles to present on the feet. It is possible but not common.

There are photos on the RSD forum of various discolorations on
the legs and other parts of the body ...

Here is a link to their photo thread. Some of the photos are dramatic and others less so. Many involve the feet so you can compare.

http://neurotalk.psychcentral.com/thread16167.html

This is an example of redness possible:
http://neurotalk.psychcentral.com/post111021-3.html
It looks like a rash but is really slightly different:

This one is redness in a stocking pattern like you describe here:
http://neurotalk.psychcentral.com/post82906-8.html

So do take a look at the thread when you can, as it might help you with diagnosis. RSD is often not accurately diagnosed, and it can be more severe than PN and present very differently.