Unknown Green Tree Frog Ailment

[Biddy]

Currently housing 3 GTF’s in an 18x18x24, they have always been active, calling, moving, and hopping. Noticed one morning that they were nowhere to be found, and later discovered them all hiding on the floor of the enclosure, the sudden onset of bizarre behavior by all three made me believe a husbandry issue, but I’ve quarantined all of them in a critter keeper to ensure eating properly and easier observation and quarantine, only to discover one of my frogs has this. Can’t find anything like it and he seems to be having trouble breathing and randomly opens and closes his mouth. None of the others have this and one has resumed normal behavior.