Sorry it took so long to respond.
How is your chicken doing now?
Take a look at this article on crops and how to treat their ailments...
https://www.backyardchickens.com/a/impacted-slow-and-sour-crops-prevention-and-treatments
I sure hope you can get her back to good health soon!
When I went to check on her that evening, her crop was back to normal, and I found something in the nest box she had been sitting in earlier that could have been a squished shelless egg, but it seemed slightly different. It was more clumped together and firm than shelless eggs are when they get burst, and less transparent.
This morning she seemed okay, just slightly less energetic. She was normal for most chickens, but she's usually very over energetic. That could have just been because there was snow on the ground this morning, though. And she seemed somehow less cheerful than usual, I think because she seemed to be making less noise than usual.
She's probably fine now though, and I'm just being paranoid.

I didn't get to spend as much time out there as usual so I don't know if she was acting that way just for a little while, or the whole day.