Chick with weird down.

[Mamashark06]

Hi I have had this chick for 1 week. It was supposed to be a week when I got it. It’s a mystic maran. It’s the same size as it’s sisters. Acting normally but it has weird down on its back/ back like dry almost. It looks better than it did last week but today this kind of super small burn/scrape seems to have appeared. Is there anything I should do or can do for her? We have 10 chicks total. She’s the only one like this. I don’t see any bugs or anything on her or anyone else.
Thankyou for any help.
Photo is today on the left 2 days ago on the right.

 

[Wyorp Rock]

Observe to see if she's picking at herself or if the others are picking at her.
I'd clean the scraped area with saline or chlorhexidine, then apply a dab of triple antibiotic ointment.

Do you provide a dust bath or box with dirt/sand for the chick to bath in? If not, I would.