I would place her back in the flock and make sure that she doesn’t get bullied. If she has been out for more than a week, you may want to put her in a crate in the coop for a slow introduction. You said that you have dealt with a resp disease in the past, so your flock has all been exposed and should be considered carriers. No need to separate.
It looks like she has some conjunctivitis and that the pink tissue is overgrown in that area, or she may have been pecked. I would continue giving antibiotic ointment twice a day. It may go away. You can order Tylan injectable online and use it orally, or you can find Tylan powder for the water here:
https://www.jedds.com/shop/tylan-soluble-100-g/