Abcess on chest?

[norwichlakefarm]

I have a two month old Black Australorp pullet who has suddenly developed a very soft fluid filled pouch on her chest. It looks very similar to an abcess but there doesn't seem to be any heat and there is minimal feather loss. She is still eating and drinking well but is more docile than the other three Black Australorp pullets. Any ideas on what it may be or how to treat it?

 

[TheJadeChicken]

Can you get a picture? Are you sure it isn't a small soft crop?