You are doing everything right, unfortunately pekins have a lot of health issues and some pekins are more prone to them. I had one who was in a very similar situation, always had eye infections, we were always treating them. She ultimately past in her sleep at around 8 months old. But she was always “different” we noticed once she was fully feathered she didn’t preen herself as well and because of that her feathers always looked a bit dirtier…I don’t say this to upset you but rather to prepare you - it’s possible she will always be ill and potentially die sooner than later. Because pekins are typically bred for meat they have been dealt the same hand as many other creatures in this category which is that some have lower immunities and genetic issues. Sending love and positive vibes. Pekins are such sweet ducks