the other day, after a pretty big water change, I noticed that one of my betta's eyes had swollen up. I hadn't noticed anything before, but now it's very badly swollen and has this white cloudy stuff on/in it. I've been putting Melafix in the water daily since I noticed it, is there anything I can do to help? (also, should he be quarantined or would that be extra stress and make it worse?)