Urinary Bladder (Male)?

I had a tendency of peeing very often and after I'm done peeing I pee more! So I checked with da doctor. He said that because my urine sample had a slight raise of white blood cell like (not exactly normal but could be considered normal) that the case came from an infection. Due to my young age (16) he hypothesized that it couldn't possible be stones. So he gave me antibiotics and a bladder pain reliever, the morning after I took the pill which was 17:00 I felt somewhat better, for like half the day. Then and 17:00 today it felt slightly worse. When do the meds actually take significant effect???