Since you just got them, it may just be stress.
Would be go to know more about your flock would help too:
- flock size(numbers, ages, genders),
- coop(size in feet by feet with pics),
- and what and how exactly you are feeding,
might offer clues to if there is a solvable problem.
If she is not up and acting normal soon(sorry powers been out),
I would isolate bird in a wire cage within the coop for a day or two....so I can closely monitor their intake of food and water, crop function(checking at night and in morning before providing more feed), and their poops. Feel their abdomen, from below vent to between legs, for squishy or hard swelling. Check for external parasites or any other abnormalities.
Best to put crate right in coop or run so bird is still 'with' the flock.
I like to use a
fold-able wire dog crate (24"L x 18"W x 21"H) with smaller mesh(1x2) on bottom of crate under tray.
Then you can put tray
underneath crate to better observe droppings without it being stepped in. If smaller mesh is carefully installed, tray can still be used inside crate.