raw red skin

[tomorton]

I have recently "acquired" a flock which has terrible mite problems..I am getting that under control with premethrin dust, DE and sprayint the coop inside with liquid carbaryl solution...the worst problem now is the red raw skin on some of the hens which isn't healing. Some are doing nicely...others look red and raw. They don't seem to be picking at each other. Is there some medicated or soothing powder I can apply to their skin?
Thanks in advance