50% water change every other day along with full redosing of meds and half dose of epsom (because you removed half the water and es only is removed with water change). 100% change weekly with full redosing of meds and full redosing of epsoms.
To dilute the kanaplex take 5 tsp of dechlorinated water and a level
scoop of Kanaplex. Mix it in and dissolve completely. Take 2.5tsp of the mixture and put it in the 2.5g tank. Toss the rest of the mixture. You'll have to mix it up fresh each time you dose.
You should be seeing poop at the bottom since it is bare. If you're not seeing poop he is constipated/blocked possibly by the infection at hand.
Dropsy is almost always caused by water quality issues, which is why I was trying to get to fill out the link.