Can Anything Help My Puffer Pull Through!?

[Coldwater]

Well to start things off my my Dwarf pufferfish has been attacked pretty badly by my Snowflake... He isnt eating anything, has his spine arked up, swims like a tank and his left eye sort of has skin hanging over it. I have turned down the current in my tank put him in the sump and some hiding rocks. Water parameters are fine. Is there any medication I can use to make him eat and/or heal? He looks to be in pretty rough shape and is not acting like a pufferfish should be. Any help would be great thanks.

Matt