What's going on with my chooks eye?

So, we have three chooks who are generally healthy and well. They don't free range as we also have dogs, but they have a large coop with a covered area filled with hay bales, roosts and nesting boxes as well as a big outdoor area which is covered in dog and fox proof chicken wire. Anyway... yesterday I went to feed the girls (we feed them twice each day as we discovered that the auto feeder was attracting rats!!) and all was well. If they are inside they always come out when I call and shake the food. Today, only two came outside so I opened the indoor area and found one of the girls sitting on a hay bale, making no effort to come for feeding. I thought she may have been sitting on an egg so I picked her up and noted that one of her eyes appeared to be crusty and scabbed over. Initially, I thought she may have been pecked or even had a run in with a rat, but I have since given her eye a good clean and I think it is an infection of some sort. The eye is not weeping at all and the eyeball, once I removed the scabbing, looks OK. I have removed her from the coop and put her in a largish cage with some hay and seed and water. She is miserable and has made no effort to eat or drink. I have syringed some water into her beak a couple of times and she is swallowing, but otherwise she is just sleeping. She does open her good eye if I talk to her, but makes no effort to move anything but her head (she does move her legs when I pick her up). I don't think she is missing her mates and I need to keep her separate in case she has a contagious infection.

What's going on with her eye?? The area around it looks a inflamed and a bit swollen, there are no injuries and I can't figure out where the blood actually came from. Now that the eye is clean (and I used some antibiotic cream around the area) there is no active bleeding and no oozing of any sort but she is not opening it at all. She is lethargic and not feeding but doesn't appear to be in any pain. Ideas??