broken feathers and darkening comb

[jggrossm]

Hi all -

We have a 2 year old Golden Buff Orptington. (Named Isabella.) Recently we noticed she has lots of missing (broken) feathers on each side of her neck, and her comb is getting dark on the top. We also have two RIRs which are a bit more aggressive. Any idea what's up with her?

Thanks in advance.

Joanna