Hello. I´ve seen green feces a lot, most of them from animals infested with parasites (mostly amebiasis) or some bacterial infections. It may be the result of the lack of food, because the bile accumulates and dyes the feces. Hope it helps.
Greetings.
Saludos.
supplement concern
Hello. As well as jannb I'd recommend the fecal and the veterinary visit (as well as the appropiate deworming).
I noticed that you didn't told us if you offer some supplement (as vitamin/mineral supplement), do you?
I´m a veterinarian oriented to reptiles and I used...