Hi this chicken is approximately 3 months old. The past few days I’ve noticed her to be very lethargic and wobbly when walking. There is also a substantial feather loss I. Her back and under her wings but is starting to grow back. Any advice or ideas. I k ow that there are older chickens that I had before her are a little mean to the younger ones. She is from a group of 5 added to the flock and she is the only one with this issue. Thank you in advice for the advice.