I'm a 16 year old male and I've had a frustrating bowel pattern for several months now. I have had off and on symptoms that start with a constant urge to defecate and which then turn into feces coming out without me even noticing, and thus I end up with soiled underwear and the like. As you can imagine, these symptoms have been very difficult to endure and I was wondering if anyone suffers the same thing or has any idea what this might be.

The symptoms follow a pattern that goes like clockwork. Here is one example:
(The dates are not indicative of actual times I had the symptoms, I just find them a good way to explain the timing of these symptoms.

September 1 - Constant urge to defecate comes on
September 5 - Constant urges make way to what can be described, at a guess, as mild to moderate fecal incontinence. The incontinence and urges will sometimes overlap.
September 25 - Just when the incontinence becomes unbearable, it suddenly disappears.
September 26-November 10 - No problems whatsoever, everything acts normal
November 11 - Urges creep up again and the cycle begins to repeat.

I should add that when I go to the bathroom I have bowel movements normal in size frequency and appearance regardless of whether or not the symptoms are present.

If anyone has any idea about this, or if you don't know the cause but have the same symptoms as well,posting here would be deeply appreciated. :-)