I may be wrong,,,,I mean all monitors show colors a bit differently, but the "brown stuff" on top of her head looks like dried blood. I've never even seen a silkie, so hopefully somebody will chime in, but you may have an issue on the back/rear of her comb.
Do you see any? You should be able to see them here's some pictures I found.
Check under her wings and around the vent area.
If you do see them you can buy poultry dust at your feed store to dust them with or some people use sevins dust. You will have to dust or spray the coop too. Put some in their dusting bath area. Repeat in ten days.