I figured out after posting this thread that it was not an actual lump, but rather just puffy feathers because she was egg bound. She has recovered now. Thanks for replying! :)
She ended up laying another soft shell egg yesterday evening... and ate it. We've never had any egg eating problems before (from anyone!). Why did she do this? Did she think she needed the nutrients? Or because it was a soft shell?
She also laid one this morning, a regular hard shelled one...
She was looking really good last night. We let her back out to free range with the flock at about 4:00. I couldn't tell by looking at her that she had been sick at all. No egg, but she's eating, drinking, and pooping.
I gave her a calcium tablet this morning. She's still looking pretty good...
I've seen droopiness before with another sick hen. This is the second time I've had a relatively serious illness on my hands, so you get to know the behavior, I guess.