I sleep on a heating pad at night because of hip pain. Yesterday I discovered the side of my leg still looked awful after at least l5 hrs. I did a search and found what it's called. Apparently some people's skin gets mottled after using heat for awhile on pain. My entire hip looks awful.....has for months and it doesn't go away....including some burn places for which I'm putting vitamin E. Now it's my leg too that has a brown mottled look.