I am just a patient, so no specialist advice from me. However, I was wondering if you have seen a cardiologist? I saw one, not expecting much but it turned out that I had the start of heart disease. He began to treat with cholesterol reducing drug and he did some minor surgery to remove some varicose veins. It helped the heaviness in my legs. So, I don't have vascular neuropathy, just the good old regular kind. My ankles and feet are sometimes purple. I have to wear compression socks which help quite a bit. You may want to get a cardiologists opinion on your purple arms and legs. Also, my brother in law had to have a small rib removed on each side of his chest. It was constricting his arms and caused two blood clots. His arms turned purple for a while prior to the surgery, but no crusty stuff.
I am so very sorry you are dealing with such awful symptoms. Someone has to give you answers. My thoughts are with you, in lieu of anything else.