Chronic Limping Hen

One of my hens, a Golden Laced Wyandotte, has had a limp for months. I'm not even sure I'd call it a limp, it's like her legs don't bend properly? Sometimes I can hardly tell, but if she's been running around a lot (usually after I try to catch her for something) then it's more pronounced. She kind of walks like a penguin. The pads of her feet also look swollen to me, but they aren't hot and there are no signs of bumblefoot (no scabs).

When I first noticed it I thought she had sprained something, so I caged her for a few days and gave her vitamins. When I let her out she seemed better, but then the limp came back. I made the bedding much deeper and lowered the roosts (roughly 3 and a half feet off the ground).

I also tried soaking her feet, but she is very flighty and hated it. Most people say their birds seem to love it but uh uh not this girl. She flapped like a banshee.

Also of note, her eggs are very narrow, but she has only been laying for about a month. She lays about every other day.

She also has slightly runny poops, so I have to trim and wash her butt fluff occasionally.

Any suggestions?