I got the term "Weak Bones" from the PoultryPedia podiatry site. It's symptoms are the closest match to what I am seeing. I have a 3.5 week old chick that I am keeping for a friend, it was the only survivor from a hatch and since it was alone, it was brought here to grow up with 6 of my chicks who are the same age. I have had it since it was 2 or 3 days old, and my chicks are not having this issue. When this one hatched 2 others managed to get out, but they had to be culled as they appeared to be severely handicapped, they couldn't walk and lacked motor control to the point where they couldn't even hold their heads up. Those 2 were from different parents, but my thought in mentioning it was a possible problem with temps during incubation making this guy more prone to problems??? Poultry pedia suggests supplementing with vit. D3 and that is already in the water and has been given once a week, it also suggests switching to a commercial starter, but that is all they've ever been fed. Also suggests increasing calcium to phosphorous ratio, but I'm not even sure how to do that. This guy will only walk a few steps then lays down, like his legs are tired or painful, he rocks back on his hocks a lot as well. Hocks are very close together, giving him a "knocked kneed" look, but the toes are still pointing forward and the tendons are both in place. I do think there is some swelling in both hocks. I started noticing the change in him about a week ago, but it has taken a few days to pin down what is going on. He seems healthy otherwise and is eating and drinking, just does it laying down. Anybody seen anything like this???