C.W.
Without actually seeing it I can't say if it is the same thing or not, but I get what looks sort of like an iodine stain behind my knees when I have been wearing shorts. It seems to be from my skin touching. I use a coco butter and shea butter cream to coat it and it goes away with nop further treatment. Regular lotion doesn't work as well because it absorbs into the skin too much.
I also use the coco butter- shea butter cream as a preventive (when I remember) And that seems to keep the rash or whatever it is away.
Hope this helps.
C.