He's doing well! Thanks for asking :) Well, at least more active than he was when I first received him, so I'm really happy to see that his health is getting better! He even makes little bubble nests now and then.
However I haven't seen any progress with his fin rot ): it hasn't changed a bit... and the aquarium store which I ordered the Ampicillin hasn't called me back yet so I'm probably going to give them a call tomorrow about it. I'm going to give him back to my friend while I'm gone since I don't trust my father to do regular salt baths and water changes for him ):