Sounds like maybe she did injure her eye. Especially since the rest are doing fine, and no respiratory symptoms.
I'd hold off treating them all since they aren't showing any symptoms.
If this one is isolated, then treat her with the antibiotics just to see if maybe the injury has gotten infected or who knows why it's swollen and the eye shut. I think it's good that you aren't seeing any discharges though.
Keeping ya in my thoughts and prayers!