I had a broody hen hatch 10 chicks about 10 weeks ago. Yesterday I found one of the chicks sitting in the corner and it’s feathers were all puffed up and it couldn’t walk. I left it in the coop, thinking it might be dead the next morning, but when I went to the coop in the morning it was sitting in another corner, pecking at the ground, but still no able to use its legs. It lays on its side and peeps every now and then like its in pain. I have 20 other chickens that the broody and her chicks have been kept with since the chicks were 3 weeks old. If it is mareks what’s going to happen to my flock?