I have beautiful black & white roo approximately 7 mos. old. Since I live in a subdivision, my neighbors are not too keen on having a crowing rooster nearby. He has not been at all aggressive with me but he has been aggressive with 2 of my older hens.
I had a hen acting the same way. I asked for advice at the feed store. They recommended isolating her and giving her sulmet in her water.
She perked up in a couple of days and was like a new chicken! Do not eat any eggs she may lay while on the sulmet. Don't know if this will work with your...