How would your doc know WHICH antibiotic to prescribe if you haven't had a urinalysis and, MORE IMPORTANTLY, a urine culture? The culture can show what type of bacteria is growing in the urine. Remember, not all bacteria respond well to all antibiotics, especially as the antibiotics have been overprescribed and aren't working all that well now. And while it's true that pyridium can help the symptoms, it doesn't actually zap the bacteria, as an antibiotic can.
Here's something simple you can do to ''help'' prevent future infections:
Boil your cotton underwear. Regular washing doesn't kill bacteria, and you can re-infect yourself.
Wear loose fitting clothes, rather than tight fitting jeans, etc. Bacteria thrive in warm, moist environments, and tight fitting clothes enhance that effect.
Don't use harsh soaps when washing. Tepid water is best.
Drink lots of water, eat extra yogurt to help promote the good bacteria which you lose while on antibiotics.
Take cranberry supplements daily, either as a pill, or whole cranberry. You could drink the juice too, but I personally don't like the taste and prefer the pill form.
Best of luck