From your pictures... I would diagnose Abdominal Dropsy.
I have not had any experience with this. But I did find a website that has a suggestion...
http://www.nationalfishpharm.com/fish_diseases/
skin_disorders.html
It's almost to the bottom.
Says: Treat with Koi Fix®, or a combination of Oxolinic Acid and Oxytetracycline in the feed at 1 tsp. per pound each. Use Forma Green in the water if the fish has ulcerations.
The other thing I found about blisters is at the complete bottom of the page... Says possibly swim bladder... Treat with Doxycycline -or-Oxytetracycline.
The swim bladder doesn't mention the bloat... So I am tending to lean towards the dropsy...
Hope this helps. 9 times out of 10 you're going to have to order the meds... I doubt a LFS is going to have them. You may try a veterinarian...
Also... I am curious about the affect on the other inhabitants of the tank... If you have a gold spot pleco... that's a more expensive taste... I am hoping that you have a species only tank... which would make it a great deal easier to treat...
Good Luck and please keep us posted!