I am sorry for your loss.
Is this another of your colony of 12 gliders that has died suddenly, or one of the sudden deaths you posted about recently?
Only a vet could give you specific information on how to treat your glider. There are probably few treatments that could be done on an animal as small as a glider to correct internal malformations of the urinary system.
If it is a kidney or urinary tract issue - and you are seeing the same symptoms in a joey - it is very possible that it is an inherited problem that you are now seeing as a result of the inbreeding that has produced your colony.
Malformation of the urinary tract can cause kidney failure and this is one of many internal defects that can be inherited. Inbreeding increases the chance that gliders will get the gene for the problem from BOTH parents causing illness to develop.
I hope you have either separated the males from the females or have had the males neutered to prevent further inbreeding.