Is there any swelling of her joints?
No fractures on the Xray?
I'd be inclined to wrap the leg, maybe splint it and see what happens.
I'm not a vet, that's for sure, but to me she moves like it's injured. Could still be disease like Marek's, but she moves like one of my hens that injured her leg running into a fence when she was chased by my dog.
Now, you must understand, I do but I don't coddle mine, so I just stabilized the leg with wrap and some trimmed down popsicle sticks for a couple of days, let her roam as she pleased. She was not pleased and seemed uncomfortable with the sticks, so I rewrapped with just vet wrap and left it for about 1 1/2 weeks (She was happy with that and learned to move very well). Then I took it off to see how she did. She still limped a bit, but it got better. This is a layer hen that self limited her activity and chose to sleep in a nest for a few days, then she moved to a low roosting bar, then finally made it to back roosting in the rafters about 12' up. She did recently present with limping again, likely from flying so far down and bad landing, so I just repeated the process. She did too and is now back in the rafters yet again. I'm sure this will continue for as long as she lives and as long as she's able to make it to the rafters.
BUT, I do also agree, giving vitamin support is a very good idea. I do use them and I feel they can make a difference.
Just my 2¢