The only thing I know about and can suggest is to find a
good seating clinic where you can research
the cushion and seating angle that gives you the best
pressure distribution and the least amount of shearing. What
are you sitting on now and at what angle?
At least that's a place to start. As for the shoes, make
sure they have NO ridges or seams inside (or you can tape
them) and that you have socks on that have NO creases.
Many share this problem and I haven't heard of an easy
work-around yet. Sensitive skin need constant attention and
a lot of trial and error.
Soooryyyyy,
Martin