Urinary tract infections or urinary blockages can result in difficulty urinating and more frequent urination in UTI’s. Left untreated it can result in serious kidney problems.
Urinary blockages (stones, tumors) can result in death if left untreated and UTI’s require antibiotic treatment so you should see your vet who can check for this as well as for cancer, prostrate and bladder overextension.
Checking your food brand might also be important as the recent food contamination problem might result in kidney failure and while there are many symptoms, less (and more) frequent urination might be a symptom of kidney failure. Check for recall of pet foods.