Unhealthy White Yin Yang Guppy

[juiceboxESC]

Hello! I have a 20 gallon tank currently holding 3 fish (previously 4), two guppies and a platy with one currently out of the tank because of health issues, a white yin yang platy. I got him a couple of weeks ago and only now he has shown odd and ill behavior. He is laying at the bottom of the tank, frequently gulping for air although I have two air-stones properly operating and correctly placed, and swimming as if he had dropsy; I worried that his illness would affect the other healthy fish so I put him in an isolation tank. He is not eating and jumped out of the isolation tank, hurting his eye (it is now slightly red at the top). I attempted to cover the tank but I believe that he jumped and hit his head because the top of his head also appears to be red. Would I be able to save this fish? Thank you so much!