I have a hen that has like a mass on the side of her neck. It is under the feathers and doesn't appear to be a wound of any kind and it's somewhere between the size of a golf ball and a tennis ball. Does anyone know what this might be it's on actually two and one is struggling to walk and stay upright it seems to be really affecting her and the other just cocks and holds her head funny, and goes on about life but I don't know what it is or how to treat it.