I have 4 chickens. 2 of them have feather loss, 1 much worse than the other. This has been going on for well over a year. We've tried dusting them with DE 1/month and 1/ 2 weeks with no results. Lately the feather loss looks much worse on the one chicken. I've never seen other evidence of mites or other parasites (inasmuch as i understand them). And 2 of our chickens are unaffected. The new issue is her swollen crop. It's pink and blue, which i'm not sure is from being exposed/irritated as related to the feather loss, or if it looks impacted/sour on its own account. We do feed them grass we pull from the yard, and we have been putting a little ACV in their water lately to encourage drinking. All investigative questions, pointed diagnoses, and practical advice welcome. BYC is giving me a hard time so i uploaded the photos to imgur. http://imgur.com/a/OeIKr Thank you!!!!!