I have a growing flock of young Australorps which are about 4 wks old now. I have one that has grown it's wing feathers and is about half the size of the rest. Another chick, which concerns me less, but still a concern, is about the same with a few more feathers. The rest of the Australorps are growing very well and have put on feathers to the point where they are coming in on their heads and under the wings. The smallest two are showing very little sign of growth and the smallest can fit in the palm of my hand like it was just a few days old. I thought this may be worms and have treated all of them for worms with a med that mixes in the drinking water. I have also given them Terramycin mixed in the water, but not with the worm med at the same time. Any help would be greatly appreciated.