Hi all! I have a small flock of 4 chickens and 2 ducks. I am very new to chickens, having only started early last Spring. I got all my birds before May of last year and have had no health issues. About a month and a half ago one of my hens started to get bubbles around the corner of her eye but had no other health issues. This happened when the weather first started getting cold at night. She had no progression, and I didn't treat her because I thought her body washop fighting it off and she had no other issues. I went on vacation last week for a week, and when I returned she was in terrible shape. Her eye is swollen shut with thick white pus and starting to get a watery discharge from the other eye. I brought her in the house and she seems to be responding well to terramycin. When I first noticed her issues I did not separate her from the flock (first time chicken owner mistake). No other birds have become sick and it has been weeks. We have had no contact with outside birds either. My question is what could have caused this since there have been no other birds before this group housed in the coop and no other birds have gotten sick? If she fully recovers, can I return her to the flock?