Anal Leakage

Hi, I am a 19 year old male and I am having a problem with anal leakage. It started slowly a few months back with a small amount of faeces stains on my shorts. Recently, I have found that it is now a combination of faece and clear-ish liquid. I also experience an over-clenching feeling in the anus region.  
I had cameras down the throat and through the anus 5 years ago which showed no irregularities and no problems with my blood and stool samples. (I had these test due to a number of minor stomach problems, such as reflux and periodical stomach cramps)

My questions are:
Is anal leakage at my age a medical concern?
If so, what points are important for my doctor to know?
What do you think that cause is?

Thanks,
Matt

[CalGal]

If you have hemorrhoids, that could result in leakage. Have you had that checked lately?