eyes very red around pupil

[sdue]

Another of my hens has these very red eyes now--one of the older ones. No other symptoms yet, but one of the pullets has been sick for two weeks. I've isolated her and until now none of the others have been infected. She has a bad odor too. Could this be coryza? It's weird because she's 7 months old and came down with this. My flock has had no exposure to any other birds or any people who have chickens. In three years of buying chicks and keeping a backyard flock of 6, I've never had a sick bird. What else could it be? She hasn't eaten or taken water for over two weeks and rarely poops anymore, but at first it was very watery stool. I didn't think she'd last this long, but still hangs on. Any advice?