Your frogs sound like columnaris to me, personally.
I will repeat again for this IF caught soon enough you might be able to fight it off. I used KANAPLEX (something I now suggest everyone gets as you usually have to order it). Shadow did pull through but his organs failed soon after - but at least I knew it WAS a possibility to fight it off. I bought him for the sole purpose to monitor every day, logged it every day, and caught it right before it hit.
Now I have not encountered the disease
recently, and it may or may not have changed from what I encountered five times over. I've even fought off a weird strong strain of columnaris!
seems like diseases for fish are getting stronger every year.
Anyways, you may want to quarantine the frogs individually, and medicate each. This stops the columnaris from bouncing around. Keep the heat about 76, as fungu loves it warmer - we don't want that!! Maracyn (or maracyn 2) works well on columnaris but again unsure for doses for frogs as they are different from fish. Don't get another fish until it is resolved.
As for the tank, break it down. I toss away substrate when encountering a vicious virus/disease, anything porous (fabric plants) are tossed away, other ornaments and the tank itself can be bleached and left to sit. Please make sure to super rinse it out! Acrylic tanks I just toss out... But glass tanks are usually fine.
To me everyone seems to encounter different strengths of the strain. Inhave reused my tanks after breaking them down and never had an issue. The breakdown time total was 48 hours for me since I let stuff sit quite a while, and usually "rinse and repeat".
Personally I just avoid blues now. It seems to be from one supplier to one store, but it is a wholesaler so I was unable to track it back.