DISCLAIMER: I am not a doctor. Take your concerns to a qualified medical practitioner. This information is not intended to treat, cure, diagnose. Your health is your responsibility.
I have had frequent urination occurring for a long, long time. You've seen those commercials, right? The ones were there was a teacher barely able to hold her bladder before the bell rang ... she was saved by the bell.
I'm here to tell you that I had an overactive bladder and I was able to find the underlying problem and I am not in the bathroom too often any more. There are many different reasons for excessive urination and they are difficult to find. My reason for overactive bladder, constantly running to the bathroom with a full bladder ever 15 minutes, was a kind of kidney failure called Nephrogenic Diabetes Insipidus.
How I solved it was doing kidney cleansing using herbs. I used the Dr. Richard Schulze Kidney Detox.
Consult a qualified medical practitioner if you feel you have reduced kidney function. Not all physicians are equally informed. Be certain to mention the testing that you need (urinanalysis proved not to work the three different places tested). Tests that would be run on the renal function panel can be found here: http://www.kidney.org/kidneydisease/ckd/knowgfr.cfm.
Until I was able to find out that it was a need for cleansing sugars, built up salts, parasites, and fibers out of my kidneys, I was able to eat handfuls of parsley to get my kidneys to properly deal with urea and hold my bladder longer.