Cranberry juice is good for the kidney/bladder. You may just need to strengthen the muscles that controle urine flow. I think the excercise is called kegals. It's when you stop and start your urination during voiding/peeing. Also during the stop time, hold it for a count of 20 or more. Increase the holding time as you get better at it. Doing this about 3 times a day suppose to strengthen that muscle, as well as improve erection hardness.
Man, I which I could hold my bladder that long.