There's a special kind of heartbreak that comes when your favorite hen starts standing all bunched up, and you can't figure out why. We see you, /u/OldFashionQuilting, and your precious Buff Orpington. Our take is blunt: don't panic, but don't wait, either. That hunched posture is a classic chicken whisper for "something's off," and the fact she's still eating is both a relief and a red herring.
A hen that age has earned the right to slow down, but a week of reduced activity and that telltale puffball stance deserves a closer look. We've written before about how Trash day turns my peaceful hens into tiny feathery T-Rexes, which is a great reminder that stress comes in weird forms, but your girl's issue sounds less like a fright and more like an internal grumble. She's eating, which rules out the most dire scenarios, but a Buff Orpington built like a feathered marshmallow can hide weight loss under all those fluff. Give her a gentle feel around her keel bone: if it's sharp, she's burning through reserves even while pecking at her feed. Compare that to the pure joy we saw in When your feathered friend turns into a puddle of pure cuteness, and the contrast is a gut punch. A happy hen melts into a pancake of trust; a bunched-up hen is holding tension somewhere.
Here's the practical bit: start with the basics she can't tell you. Check her crop first thing in the morning (before she eats) for any hard lump or squishy sourness, a slow crop is a common culprit for that hunched look. Then run a finger under her vent; pasty butt or a stuck egg can make any hen clench up like she's bracing for a storm. She's three and a half, which is prime time for reproductive issues like internal laying or egg yolk peritonitis, and those won't show up on a feed check. The biggest clue you've given us is that she's "still eating", hens in real crisis usually stop. That buys you time, but not infinite time. If you don't find a physical cause within 48 hours, a vet visit with an avian-savvy hand is the kindest cluck you can give her.
The scariest part of chicken keeping is how fast they hide illness until they can't anymore. You've caught this early, and that's your ace. Watch for one specific sign over the next day: does she walk away from a treat she used to love? A Buff Orpington that turns down a mealworm has crossed a line from "off" to "in trouble." We're rooting for you both, and we mean that literally, rooting through her feathers for clues, not just crossing our fingers.