Although we are not

Although we are not veterinarians, could it be that your dog might have a urinary tract infection? You can search online for "urinary tract infection" and "dog" for some more information about this. Or, it could be something else that is upsetting her (physical or emotional).

Would your vet (or vet technician) be able to at least offer some advice over the phone? Would there be another vet in the area that would allow payments over time?

The ASPCA has some advice on financial aid for vet bills. See the following, then under "Pet Care" see "Financial Help With My Vet Bills"

The Humane Society has a page as well:

Local animal shelters may also be able to advise you about care or aid.

Hope this helps!