Problem with Cochin's Leg

[Limey]

I have a standard Cochin pullet which, until recently, was moving around normally. I've begun to notice when she runs it's a clumsy gallop. I've checked her legs and neither seems to be swollen and she didn't seemed to be bothered with pain when I touched them. But about a month ago she had sour crop, could that have had something to do with it?