Kathy,

I'm guessing that if he has to assess your heels, he's going to be planning on touching your legs (for instance, holding up your lower leg so that he can see the movement of the muscles of your lower leg and foot when he asks you to flex/dorsiflex your foot, etc). If you have skin discoloration in your RSD affected areas, seeing it might be able to help him handle/touch your legs without touching the painful areas.

I'm not a petite gal myself, so I do understand the desire to "cover" things. I don't have RSD of the lower extremities, I can't imagine shaving my legs near an RSD area, which would also make me want to cover up. You might consider a long loose skirt that you could hike up during the exam or wear the shorts underneath.