Hey all. I'm new to chickens. I have 4 hens. All Plymouth rocks. One partridge, three barred. The largest barred has a yellow film over one eye and it looks a little swollen. She doesn't have any other symptoms. Is eating well, alert and active. Do I just assume she scratched herself or is this a disease symptom. Apparently she's had it for a couple days now--we were out of town and had a neighbor looking after the birds. Thanks!