I'm treating a hen with vent gleet right now, and I'm just doing Monistat 2x daily topically. However, I was talking with someone who said she had a hen with stubborn gleet and she realized it was the result of untreated sour crop that had spread to her chicken's whole tract. Is that s possibility? If it is, you can feed the Monistat orally, or so I've read. Someone used the suppository and just cut it into thirds and fed it orally. Some just put the cream in their beaks. You'd have to do some research on it because I don't know the dosage off hand. Wish I did so I could be of more help.
This is frustrating! It seems like you've been doing all the right things...