Hello.
You said both "he" and "his" but you also said female. Do you know for sure which gender you have?
Where is the sore? On a wing or under a wing?
Is he making it bloody?
Are there any actual bare spots anywhere on the bird, other than maybe the sore spot?
How long have you had the bird and how long has this been going on?
Have you noticed any change in the appearance of the droppings?
Please tell me what you feed everyday?
The extra information is needed for me to be able to give you my best advice and answers. Thanks, Patricia

