Pekin duck with foamy eye? What else is wrong??

[Snookbutton35]

Hello. I got him from my aunt sometime late last year and he seemed fine. He managed to integrate with the rest of my pekins and was fine. A month or so after getting him he got bullied by my Muscovy ducks and they ripped all of his bottom features out. He was then separated and given space to heal up. Ever since then he has only been declining. He can’t walk without tumbling around every few steps. He has foamy eye and if I had to guess a respiratory issue. He mouth breaths. And now around his eye he is losing feathers. I started saline washing his eye and using triple neosporin. What else could I do to help him?