crop problems?

[greenpasture]

I am new at raising hens. Bought six hens but didn't notice when I bought them that one hen had a large breast. She was 12 weeks old when I got her. I have had her a month now but have not known what to do to treat her. I do not notice that she smells sour. I have not noticed any regurgitation. Her poop is an orangish brown color. There was a day when I massaged the "lump" to determine what the problem was. It did seem to go down some the next day. It has since become larger than before. She is very thin as if she is wasting. Is there any hope in saving her or should I put her out of her misery? Help!