Have Smooth Rash Like Covering On Groin And Upper Thigh Area, Looks Like Faded Blood Dots. Underlying Cause

Hello. About 2 weeks ago, my daughter noticed a smooth rash like skin condition that was covering her groin and upper thigh area. Aslo behind one knee. It doesn't itch or bother her in any way. She said she wouldn't know it was there if she couldn't see it. Her skin is very sensitive and she has a severe case of karatosis polaris, so I figured she was just having a reaction to something. However, it has not gone away. It has lightened some and looks sort of like light brown bruising...like could be caused by gripping the skin too tightly. The skin looks like it has tiny, faded blood dots..like it's been pinched. Can you please tell me if this sounds at all familiar. Thank you!!