For future glider owner searches on this site-
The vet believes he had cutaneous lymphoma
Started with a dry bald patch on his shoulder (that's why I originally brought him to the vet).
Then turned into an open sore.
Lost the hair on his face.
Patches of red bumps, with yellow crust on face and back.
Then more open sores.
And finally slimy, yucky belly.
Antibiotics had no effect: baytril and metronidazole
Steroid had no effect.
Went from the dry patch to death in about 21 days.