I agree, it does certainly sound like she is egg bound. Check really good below her vent towards her belly and make sure it is not hard.
Other than that, I just don't know. Try to keep her comfortable (maybe give her a heat light?) until someone else can come along and try to figure it out.
Check her vent, she might be egg-bound. If it is very swollen and hard below her vent, that's probably your problem.
I've never 'fixed' one that had egg-binding, but I'm sure there are some posts on here telling about it. I had a goose last spring that was egg bound for a few days, she laid...
The cold doesn't affect them much at all, mine are outside all winter in temps to the teens at least. Has she laid any eggs since? How often was she laying before? Does she have any labored breathing? Did you check her vent?