There actually could be several different reasons why she's acting this way (which I'll list below) but given her breed and their tendency to develop problems with their spines, I'd probably want to consider this first. A frequent problem with Dachshunds is that compression of the spinal cord by a disc is often seen... the degree of compression varies from mild (where the patient might act as Stella is doing) to fairly severe (the patient is paralyzed).
The other possibilities include:
1. Bruising or a strain/sprain or pulled muscle such that she's unwilling to move/jump as she's used to doing. Typically, a localized area of discomfort or pain can't be found.
2. As strange as it sounds, I have seen some dogs with anal glands behave as you describe. If you are not familiar with these glands, the following link discusses them in detail: http://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=625
Some dogs are extremely bothered when these glands fill up which causes pressure on their bodies and will continue to do so until they are emptied. Although a groomer can provide this service for you, they usually attempt to empty the glands externally. The better method is done rectally which is how a vet tech or your vet would empty them.
3. Tick diseases can also cause some dogs to behave this way although they're usually also running fevers ...although not all of them do.
But, regardless of what might be the problem, since she's not taking any medication and not vomiting (I assume), then otc, human Aspirin can be given at a dose of one, low dose, 81 mg tablet twice a day, with food to avoid stomach upset. The anti-pain as well as anti-inflammatory properties of this drug may help to provide relief.
My only hesitation about its use would be that it might interfere with what your vet would want to prescribe if she has to be seen; however, one or two doses should be fine.
Hopefully, this isn't anything too serious but if she worsens in any way and/or doesn't seem better by tomorrow, then a vet visit may be wise.
I hope this helps. Deb