I have to say I've never seen a cutaneous case of Mares or even pictures before. That's awful from the looks of it. I'll be trying to find out more about that. There is so much knowledge on this forum that's awesome!
It looks the the mange i treated a guinea pig for. It's caused by a very tiny microscopic almost lice/mite. I used Ivermectin. Are you familiar with it? The first thing is to get her clean up. A bath. and get some Vetricyn and spray on 2 or 3x a day. Start giving the Ivermectin as soon as you...
Welcome to BYC!! Please do post photos. From your description it sound more like lice. But I don't know. A Bath would be good but won't kill anything maybe just make her a little comfortable for a while. Be sure to dry her thouroughly. And check out the feather shafts extra close up. Good Luck!