My silkie has a growth
How does it feel--soft, smooth, firm, irregular, or like it could be air under the skin? If it is soft like it could be an abscess, I would try to lance it to see if there is any purulent drainage or a core under the skin. If it is more firm or rough, it may be a tumor which can be common. Chickens can suffer an injury and get a leaking air sac which collects under the skin. Can you feel her crop separately from this growth?