I have an EE that started slowly losing the feathers at the base of her back and just above her tail about 3 months ago. Nothing alarming just noticeable. She is now mostly bawled in that area and looks stressed. Her blue eggs also have a coarse black dust that I thought was just...dust but now I am not sure. No other hens (i have 4 ) are going thru this. I use DE everywhere and have since this past January. I do not see mites on her or on any feathers that have dropped. Her skin is stabbing up. Any help please!