you need to check her for bugs. Look around her vent, under her wings and under the feathers of her neck. Use a flashlight and look fast, they move quickly. She looks miserable. Treat all the chickens for scaley leg mites, coat their legs with Vaseline (petroleum jelly) at night when they are on the roost. Five nights later do it again.
you'd do better to switch to an all-flock feed with a higher protein content and serve oyster shell in a side dish. Chickens that are not laying do not need a layer formula, it contains more calcium than is good for them.
her crop should be nice and full at night and empty by morning.
Feel her undercarriage from front to back. Does her breastbone feel sharp and pointed or does she still feel rounded and meaty? Moving toward her legs, how does she feel? Does she feel squishy like she's full of water? Compare to another chicken. Between her legs and moving up toward her vent, does she feel unusually full like she could have an egg in there somewhere? And finally, do you have a glove? If so, gently insert a gloved finger into her vent up to the first knuckle and see if you feel an obstruction like an egg stuck there (I don't expect you will but you should check). Take a good look at her vent, use a flashlight and just make sure everything looks normal back there.