They have a dust bathing boxnin the coop with pellet stove ash, play sand and DE,,. They have less dust and a cleaner coop than my house! I have sprayed walls with goat&sheep spray and ensure extra feathers are out of the coop and changed bedding weekly. I spotted about 3 birds going to town on their heads, itching the tops no their heads, again..It is so hard to inspect chickens heads, however there were 2 birds with small amount of nits on their bums, that is all I could find. I treated their heads under wings, bums, with neem oil mixed with olive oil and dabbed with q-tips. Paying special attention to the neck head area. Sprayed what nits were found with goat&sheep spray. I also rolled on hydrated lime with water on the walls of the coop and cracks... The only thing left could be the problem is ear mites? I have no idea how to check their ears for mites or signs and symptoms or if chickens even get them.. I have 12 chicks in the brooder and determined to get these issues taken care of before moving the babies to the coop. Thanks for the help!