What exactly did the vet say was wrong with her? You said "phenoma" - did you mean Pneumonia - a lung infection?
It takes a few days on antibiotics before you see improvement in most infections including pneumonia.
Your vet will give you specific instructions when you bring her home about the medications to be given. Continue the medications as long as your vet directs you to, even if your glider appears well. Not completing a full course of antibiotics can result in a rebound of the infection that may not respond as well to the antibiotics a second time. You should be able to feed her as usual when she comes home, but I would offer lots of very juicy fruits like watermelon or cantaloupe to help keep her well hydrated.