I have 13 chicks, and 3 Buff Orp's. Two of them are the same sized but the third is so much smaller. They started out all the same size but now she is just 1/2 if not 1/3 the size of the other two. She seems to be coming to her feathers more slowly too. I have been watching her and she eats, sleeps, drinks and plays. I inspected her and she looks fine. What do you think? Dwarf, or a medical problem?