I have read so many threads on this subject. No vets here will see chickens. Do you do a full clean out of coop? I already did that in late February with Elector PSP. I. no longer have that (psp). All signs point to depluming mites.
Back in late February/early March I treated entire flock with Ivermectin. 2nd dose 10 days apart. Found new patches on 3 different hens. Skin is crusty and two others skin is red. I have a flock of 21.
Can they return this quickly or is it that the Ivermectin did not eradicate the mites...