Anything hard and big enough to block the crop from emptying, that’s what you’d feel for. Since she’s been under your supervision inside most of the day past few days, I would think she wouldn’t have eaten anything to clog things up, but it’s always possible.
There is this theory; if she has been suffering from an overload of worms, they may be clogging things up since dying off. Again I can’t say for sure this is what is going on, but just an idea, give this post a read (#27 by
@azygous);
https://www.backyardchickens.com/threads/%CA%80ᴇ%EA%9C%B1%E1%B4%8F%CA%9F%E1%B4%A0ᴇᴅ-hen-suddenly-falling-asleep-while-standing-droopy-tail-𝘌𝘥𝘪𝘵-𝘗𝘳𝘰𝘣𝘢𝘣𝘭𝘦-𝘞𝘰𝘳𝘮-𝘉𝘭𝘰𝘤𝘬𝘢𝘨𝘦.1628022/page-3
Do you see any worms hiding in her poop? You may want to try conservatively treating her crop (as n̈you have been this morning) before jumping to the treatment in that thread.
Important to keep up with the sugar water/electrolytes to get her through this.