Look up what to do with egg bound chickens - lots of great resources for this! A broken egg can lead to a much greater risk of infections which can be fatal, but there is a chance she can pull through.
I haven't experienced anything like this directly, but there are some ways to narrow it down.
1) Does her crop empty overnight?
If not then impacted and/or sour crop is very likely the cause - especially since you say it's full. There are very clear instructions on how to treat these conditions...