I think you should consider looking into the
www.lizajane.org site for lists of the testing for PN.

You also should probably have a 'skin punch' biopsy test done.
It is non-invasive, and has no after affects.
(see the recent topic 'Skin Punch...Gold Standard' )

If no facility near you does one, Johns Hopkins has a kit with
instructions, and how to send it back to them - for analysis.