It will take time for their new feed to sort out any issues.... ie weeks or months even. I would be extremely surprised if they all have vent gleet. It is more likely that they are all carrying too much weight (fat) from the previous feed and their poop is soiling them because their back ends are so plump, the poop cannot drop free of their feathers. The bad smell is most likely because she was backed up with poop. The longer it sits inside them the worse it smells when it comes out.
Good to hear that she is eating well and pooping better.
Good to hear that she is eating well and pooping better.