Diseased Bird: Sick female Cassin’s Finches

At least 5 female Cassin’s Finches at my feeder have presented with the following symptoms: Fluffed feathers, closed eyes, lethargy, self-isolation from flock, excess time sitting on bird bath and drinking, excess time sitting on feeder and eating, inability to fly, and finally death. I examined one dead bird– there were no external injuries, fecal matter was white and green. Toxicosis? I have not see any ill male Cassin’s finches or ill birds of any other species at the feeder. There are two females still hanging around the feeder that look sick– rest of flock seems to have migrated.