why my ex-battery hen throw up?help pls :(

hi
my ex-battery hen throw up since morning.i am worry about her health.and also i have another 7 hens in the same coop.why she throw up?

Hens can't throw up in the same way we do becasue they don't have a diaphragm.

If the bird is sicking up food/water, it is more likely to be a crop blockage so the food can't pass from the crop into the gizzard.

I would seek the advice of a vet.