I hatched out 2 barred rock chicks a week ago. The larger of the two (who had been doing better than the smaller at first) suddenly has developed what appears to be splayed legs. This chick had been walking around with NO issues until the past 24 hours. I'm confused, as the smaller chick who had issues getting out of the shell was the one I was worried about. They both were just fine up until the past 24 hours, though. They're too young to show any signs of Merek's from what I read. They weren't vaccinated (I wasn't really expecting any of the eggs to hatch, and most didn't), but all of my adult chickens (including the parents of these two) were. I was told it was too late to vaccinate them at 4 days old. I'm concerned about why this chick would suddenly have issues with its legs when it's been healthy appearing and hearty since coming out of the shell. I raised 13 chicks (including the parents) from day old chicks...so I'm not new at it. It was the first time I'd used an incubator, but the smaller chick is fine, and as I said there weren't any issues until the last 24 hours. How does a chick suddenly go lame? Any ideas what to do about it? The chick is able to make it around to get to food and water, but isn't able to stand on its legs. I hadn't intended to keep the chicks, I had hatched them to sell.