So I currently have a 10 gallon tank with 1 betta fish and two ADFs. The tank is filtered, heated to 78-80, and cycled. Parameters are okay (0,0,<40). I have had the betta about 2 weeks and the ADFs about one.

Recently I noticed that one of my ADFs has a swollen eye. Over the past few days it has gotten worse and turned red. I am very worried and want to do everything that I can to help him out! If anyone could provide any advice it would be greatly appreciated. He is eating normally but is acting somewhat lethargic and hiding a lot. I am thinking maybe it is a bacterial infection? I have heard of using primafix, melafix, and maracyn 2, but I am not sure. I was unable to attach photos so I uncluded a link. Thank you so much in advance!
http://imgur.com/a/bbUkX