I research it could it be a secondary infection or?? Ill try to answer any questions you have!
Here are some pictures
Her normal eye
Her swollen eye.
Does she have a runny nose, wheezing, cheesy material in the back of her mouth? That could indicate a respiratory infection of some kind, especially since you said she was exposed to it--respiratory infections are highly contagious. When you smell her face area, is there a foul smell? That could indicate Infectious Coryza. Does she have any other symptoms?
BUMP! Hope a guru drops in! That's VERY swolen! Do you have saline solution to flush the eye with and triple antibiotic eye ointment or Vertacyn opthalmic gel? When you were treating the other 3 for URI, did they have any similar symptoms? If you have antibiotics, I'd start her along with vital pac or similar to keep her boosted. Best I can do for you, best of luck and please keep us updated.
Tylan 50 when given by mouth usually takes longer to take effect, as opposed to being injected intramuscularly with a 22g needle. If I was using tylan by mouth I would do it for at least 7 days. Always make sure to feed a probiotic (like sav-a-chik) during antibiotic treatment to keep her immune system running well. Is her face swollen and hard? or does it feel kinda soft. I'm wondering if you could use a topical eye wash. Hmmmmmm. I'm sorry I don't have a lot of experience with diseases like this (my specialty is bumblefoot )
Is she still eating/drinking normally?
I'm going to do some research for you and see what I find
To flush the eye, contact lens solution is fine. I would pick up some either Vetracin gel or triple antibiotic opthalmic ointment. It's good to have all 3 on hand. I'd do a full course of antibiotics as well.