I had 11 chicks hatch on July 3. I am concerned about 2 of them. 9 of the chicks are feathered out except for their heads. The other 2 only have feathers on their wings...no tail feathers, only fuzzy yellow or black baby fuzz everywhere except their wings. There has been nothing different for these 2. Everyone eats and drinks the same things, sleeps in the same place, and plays outside in the same pen. They are all the same size too. What gives? Should I be worried?