I'm very sorry for Luigi's death. Saw your post today but had little to add to Grif or Jessica's sound advice.

Not sure if frogs osmotic systems are like fish; but many people are confused about salt and it's effect on them. If you suspect the organism is retaining water, adding salt (NaCl) to water is counter-productive. What you can do is add Epsom Salts (Magnesium sulfate) at rate of 1 tablespoon per 5 gal. of conditioned water and that will help ease water bloating (also used as a laxative for fish). Be aware if organism has lost renal functions (i.e. advanced case of dropsy) it's doomed.

Also, recommend not placing all trust in a bottle of water conditioner; they are chemicals that lose potency with time or need to be double or triple dosed in some locations. I learned that lesson when doing full water changes on betta jars and almost lost 6 fish. The bottle of conditioner was almost empty (exp. date was good) and a test for Cl (I use Red Sea's Cl test kit) proved positive. Since then use Seachem's Vitro Alpha with great results and test my conditioners every quarter.

If you suspect Chytrid Fungus, would throw away all substrate and organic or porous decorations can't sterilize. Then wipe tank, cover, plastic decor, and anything non-absorbent with a new cellulose sponge or similar soaked in unscented clorox (wear eye protection/gloves, old clothing and do in ventilated place). Let it be for around an hour or until clorox evaporates and then do a couple water rinses with tap water and a final one with water over treated by conditioner 4X the standard dose. I've done this before and used tank/decor with fish & frogs with no problems. Good luck!