My silkie Lola is a 5 weeks old and has a sibling Lolita. I got them from family, farm & home and noticed no issues but put them both in a brooder by themselves (they were bigger than the other chicks by a lot). Recently we got 3 small Rodies from the same place and put them in with Lola and her sister. After a short time I noticed all of the chicks were scratching near their ears and on their necks. A few days after, Lola had no feathers on the back of her neck, it is very swollen and a pink green color. I had no clue what to do so I applied some triple antibiotic ointment to the area and placed her away from the others so they wouldn't peck at her bare neck. What should I do? Could this be causes by mites/lice? Help!