We have 9 Rhode Island reds and one chicken has been sniffling quite a bit lately. I'm guessing it might have a cold? But all my hens get together and bully this hen. They mount her and peck at her neck. At night she sleeps by herself, and when we let them free range the bullied hen secludes itself away from the group. The bullied hen has been looking a bit thin lately. What should I do plz help.