How's it's crop look and feel? could it have eaten something that has possibly caused a blockage?
Another thing you could do is make a soupy mash out of it's feed to give it some food, more like water than food but if it's drinking it may drink this and just use the electrolyte water to make this up. Have you ever used a flush on a bird before? in the sticky's at the top of goose thread there is a link to toxin flush and the molasses one is the one most use.
I would think at this juncture that any means of good flora in the digestive tract is better than none. I could be wrong. I will go on the Veterinary Formulary and check the Avian stuff.
