Thankfully its getting better now, she doesn't seem to have a sinus infection because there's no puss visible in her eye. For now we put her in a separate coop but I was wondering how long she should be separated from the other hens...
We took our hen to the vet and he said she certainly has an eye infection. He prescribed antibiotics for a week to be taken in her water, and eye drops. Has anyone had experience with this before?