Looks like a prolapse to me. Very young for this type of thing to happen. The above advice is all sound. I have some concerns that she has underlying problem that wold cause her to prolapse when she is not even old enough to lay an egg. To decrease the swelling you could make a solution very concentrated sugar water and smear it on the prolapse. This is an old farmer trick to decrease swelling. When my Wyandotte prolapsed, the sugar solution helped decrease the swelling instantly. Also, I would give her a epsom salt butt soak to help keep it clean. Peritonitis, which is an infection of the abdomen, is a big concern.