Same for my husband post radiation 12/26 (last session) , the frequency has gone to every 2 hours from hourly. When up every 3 hours. And he’s gotten to every 2 days on Flomax as it was making him dizzy, seems to help. My guess is urethra was hit near prostate and swollen so not completely emptying bladder each time. Swelling must be coming down as frequency becomes less and burning with urination improves. Hang in there.