This may be a long shot, but I have to ask....is she acting broody? While the green can be from feed, grass, or illness, it also looks very similar to broody poo. Her behavior also sounds like she is brooding in a corner. Some hens will poo in their nesting spot, and it will coat on their behind. Broody poo is enormous, sticky, smelly, and often has a green tint to it. The hen usually has one very large bowl movement a day, and those that are obsessed with the nest won't even get up to relieve, which is why it coats their behind.
A brooding hen can become fixated on a spot even without eggs under them, puffed, and grumpy at anyone or any thing that comes around them. They will sit fixed and staring into space like a trance. When you pick them up they will rouse, but want to immediately return to that spot they've chosen for brooding...which is why I ask since many sick birds will "hunker down" wherever they are placed as they don't feel well while a brooding hen will almost always return to her brooding spot.
I've had hens go broody at all times of the year. I've hatched numerous chicks under a broody hen in the dead of winter.
However, if she looks sick...hunkering because she is weak....then obviously this would be a sign of her illness.
Edited by Lady of McCamley - 1/8/16 at 9:26pm