It's probably an absess. Is the area hot? Im pretty sure chicken have a higher body temp. If the are is hotter than the rest of the chicken then its an absess. You coud probably drain it and give it antibiotics. Or kill it and burn it. Are the other chickens picking at it? That is another way to tell if it is sick.
Thank all of you so much, kev the video helped as I was a novice at the upside down chicken boob massage. I did get alot of fluid out, but it feels like there is a lump of sand/grit in there. I'm goona try again in a few days.
She and the turkey stay in the coop, all of the other birds free range (30 chickens and 10 ducks). She is one of my older birds about 2 years. I have fed my birds mostly cooked corn, wheat, rye, and barley, but I cut that out when I installed an automatic door about a month ago. I just keep cracked corn in the feeder and let them take care of the rest.
Ok, she has had her upside down boob massage weekly and been treated with apple cider vinegar. It feels like there is sand in her crop after I get the liquid out. It seems much better at times then swells up. Also, she is moving her head around like she is a girl acting like a chicken. (I hope that makes sense)