He's at 0.5 teaspoons Epsom salt per gallon now. You could bump it up to 0.75 teaspoons, and see it that makes a difference. (To give you an idea, I'd recommend 3 tsp/gal for a more severe disease. So he's at a pretty low dosage.)
If you've already done the water change, just take a small amount of conditioned water and add the other 0.25 teaspoon Epsom salt. Stir until it's dissolved and pour it into the tank.
Since water changes are stressing him out so much, you could do partial water changes instead. He's in a 1 gal tank, so you could just do a 50% water change daily. This will keep you from having to chase him with a cup (or net), and probably make you both happier.
(I know the feeling; one of mine gets hysterical when it's time for his water changes.)
To do a 50% water change, using 0.75 tsp Epsom salt/gal (in a 1 gal tank), you could:
1) Remove 50% of the water from the tank.
2) Fill a 1 gal container with water at the same temp. Add conditioner.
3) Add 0.75 teaspoons Epsom salt. Stir/shake until the salt is completely dissolved.
4) Add back half the water (25%). Wait about 10-15 minutes (for acclimation.) Add back the other half (25%).
5) Keep the remaining treated water for the next change.
I'm glad the extra humidity is helping.