My 4 year old pom has the same thing. I am taking her to the vet on monday. I hope to God its only a urinary tract infection. I can not afford a bunch of tests either!
I just spent almost $600 for a bloody urine workup on my dog.
If the antibiotics don't help, you'll have no choice but to go back. My dog had a UTI, but we had to have xrays to rule out kidney or bladder stones, and a urine culture and sensitivity to be sure he was on the right antibiotic.