*UPDDATE PIC ADDED* what's wrong with her chest raw and irritated/bald

[Minx]

I would definitely treat for lice ...

 

[silkiechicken]

I'd check for bugs but to me that looks like she is starting to moult due to pin feathers showing, but that someone, possibly her, saw this and has started plucking. Upping protein may help during this time.

My cochin and cochin x's moult badily and heavily, while others do it discretely.

 

[mtngirl]

Do you have any white leghorns? We had some but they started picking out the other's feathers. It was really bad.

 

[Hardy Hen]

she's molting that's it. their skin does look like it hurts a lot and it does hurt but the feathers will grow back. if she is pulling the feathers out then you could put a warm water and vinegar solution on her so she stops.