Phil's Rambling Rants
If she isn't in pain, you can just make her comfortable and take her in the morning.
Our old dog scared us badly recently because he suddenly couldn't stand up on any kind of non-carpeted surface. We were afraid something was seriously wrong. When we took him to the vet (named Melissa - are all vets named Melissa?) she told us he had a pinched nerve or inflammation that was causing him to lose all feeling and activity on his left side. She gave us some prednisone and within a week he was standing and walking and trying to be a puppy again.
He has since gone downhill a bit as we tailed the dosage off, so the vet is having us put him on one pill a day again.
The important thing here is that it might not be the worst thing you can think of, and the concern should be whether she is in pain as opposed to being worn out from trying to stand or just frustrated for now.