Need Advice on my Goldfish

I have been looking around and browsing the net about what our favorite goldfish really afflicted with. I hate to loose this one on the video below because he's got really nice fins and he's getting bigger now. Sadly the fins and tails are the first ones showing symptoms. We thought he would grow healthier than he is but too bad he's having some disease we aren't really sure what. That's why I'm seeking any advice from anybody who knows about these stuff and those who had an experience like this. We thought it's Ick so we started the treatment with those tablets that we bought from the pet store, we're on the third day now but it seemed a little different from the symptoms of Ick that I read about. Or is it Fin Rot? Yesterday he started looking like he was really tired and just wanted to stay and sit at the bottomof the tank and then after a little while he would swim like normal again. I hope it's not too late yet. We really want to save him. Please share some insights about my situation. Thanks.