Hi and welcome to our forum,
I know some neuro’s say if your feet are affected they would be looking at possible lower spine pressure , and if it was your hands that were only affected then they look at the cervical area, this would be a good one for Glentaj to answer because I can remember him saying that cervical problems can affect your feet too.
Have you had a post op MRI of your cervical spine ?

I know through my own experience with B12 that I
had worsening of symptoms whilst my nerves were actually healing..
It may help if can post your first b12 reading, and then the last one you had, and how often you had the injections and over what period of time.
There will be others along shortly and they will try to help you too.
Here is a site that is worth while looking at, its still under construction but its written by our B12 expert, Rose.
http://roseannster.googlepages.com/home
This one shows all tests that can be done for PN
http://www.lizajane.org/

I would also suggest that you look at the stickies on the front page and up the very top you will see them.
Brian