geebs - how's your girl this morning?
I'm sure you found some good info. on here - wish I'd have been online when it happened...something if they're trying to pass a shelless egg they act extremely ill until they lay it. It's the oddest thing, and I've had several hens in the past that I witnessed doing this. Every now & then, a softie is laid, but I think we typically don't see it because they break so easily, and, well...they get eaten.
BEST course of action is a warm bath for 10-15 mins. if they are truly eggbound, which is what it sounds like you did. It's never a good idea to go poking around the vent unless you see shell fragments or yolk coming out, though. HOPE she's doing better today!!