Hi I am completely new to chickens and have a brood containing 2 Buff Orpingtons and 4 "brown layers". The Buffs are about 8 months old and the brown hens are 5 months old. They get to free range for an hour or two about 4 time a week. One of the Buffs has been losing feathers on her neck, some missing and some looking broken, for about a month now, she has also stopped laying and had an occational sneeze. The skin on her neck seems a bit white and flaky. The rest of the birds seem to keep her at a distance but I haven't seen anyone pecking at her. She has gone from being quite cuddly to pecking at us whenever we try to touch her. I looked for parasites but didn't see anything but I'm not sure what I'm looking for. The rest of the bird seem ok and are laying. I have attached a pic of her neck. Any ideas would be greatly appreciated.