Hi! I have 4/5 week old chicks, first time! We have 7 total, 4 cream legbars, 2 barred rocks and 1 welbar. Everyone has been doing well and getting along, but our welbar, cookie, has been a bit of a loner. Today when I went to check on them I noticed that it seems she has missing feathers on her wing and it looks bloody/injured. I have no idea what could have caused this, I’ve never seen her be bullied. We are expanding to a bigger brooder, right now they are in a 40 gallon tank. What should I do from here? How do I treat the wound? She doesn’t like to be separated she absolutely freaks out. Any advice is helpful please! Attached pics