Hi! SO frustrating that they can't tell you what's wrong -it could be lots of things including just having a bad hair day!
How is she toileting? Any signs of upset tummy / constipation, pain or temperature?
I've never had bitches so have no idea if it might have anything to do with coming into season but logically, its all hormone related, so could have something to do with it I'd guess.
I would just wait and watch for the next 24 hours, there's not a lot of point seeking out the vet until you have any real symptoms.
Unless she attempts to toilet in the house, I don't think I'd force her out, just leave the door open for a while and see what she does - I sometimes think trying to coax them seems to increase the tension, - it does with Humphrey anyway.
Plenty to drink, warmth ,rest ,light food and lots of TLC is a good place to start and then just see how it goes.
Sending
, let us know how it goes! they do worry us don't they ?