Chicken with totally bare back....what should I do?

Okay....I don't think it was the rooster pecking at her. She is losing all of her feathers. I built a quarantine area for her but what should I do for her? I have some dust stuff but it sounds scary because they say to wear long sleeves and pants and chemical proof gloves.

What the heck kind of dust is that?

Obviously the wrong kind. It's all that tractor supply carries. Where else can I go to find something safe for her?

I know some say sevin dust but thats now banned from use on poultry... I know there another other sugest i dont rememeber what it is through let me see if i can find out and while i am looking maybe some one can answer.

Found this hope it helps
Treatment should begin immediately upon identification of lice or mites in any flock member. There are many different products available to eradicate mites and lice with varying degrees of effectiveness, among them are: Garden & Poultry Dust with Permethrin, Pyrethrum Dust, dog flea dips, flea shampoos, Poultry Protector, Sevin Dust 5% (carbaryl powder) and Ivermectin. When lice or mites are detected on one bird, the entire flock should be treated. Treating birds after dark when they have gone to roost is the easiest way to treat the entire flock without having to chase anyone.
I use Sevin Dust 5% to treat my chickens. While wearing a respirator and with the help of another person to hold the bird, I dust underneath the wings and vent area of each bird sparingly but thoroughly. I also clean and treat the entire coop with Garden & Poultry Dust with particular attention paid to nests and roosts.
An extensive list of treatment options (with application rates) for eradicating poultry pests including, lice, mites and fleas, can be found at this link to the Mississippi State University Extension Service.
**Treatment for lice and mites must be repeated twice after the initial application in 7 day increments, in order to kill the eggs (nits) that had not hatched at the time of the previous treatments.**