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Hello. Thanks for the question.
With that history, I wouldn't wait around to get her seen. I would get an exam tonight. It's possible that she has a clot stuck in her urethra and she's not able to empty her bladder. If that's the case, then she'll likely need to be catheterized.
If the bladder is small and it's a UTI (urinary tract infection), they can get her on some antibiotics to get the UTI and diarrhea under control. It's not uncommon for diarrhea to predispose to UTI's in dogs as they can get ascending e.coli infections up the urethra.
If she is straining without producing urine, then yeah it's possible. If she's still able to pass urine and some blood clots, then it may just be a bladder infection. I worry when there is straining and no urine production for more than 6-8 hours.