Hi! I'm new to chicken raising and we have 5 rhode island reds for about 2 months now. They are about a year old, we bought them from a large scale organic chicken farm. From the beginning several of them had missing feathers, but we attributed that to the stress and roughness of moving. However, two of the chickens continue to have bald spots on their backs right before their tails. And this morning I noticed that our favorite, Henrietta, has an area of missing feathers on her back, a small sore, and a bump on her tail (next to the oil gland). We've used poultry dust on the chickens last week, due to concerns about the missing feathers. Any ideas??