Are you having other digestive problems too? constipation, gas, bloating? Any other symptoms at all? I started having bowel problems when I was your age and now I too am having a feces odour at times. I also suffer from constipation problems and other digestive problems too with many other symptoms. I really think that cleansing is important when it comes to these types of problems and I really don't think your age should be a problem. Also, are you currently taking the birth control pill,exposed to any types of environmental toxins, or have taken courses of Antibiotics ?
Many people here feel that P and B shakes are a great way to cleanse the bowel and I have been taking these along with doing colonics at times. Also, what is your diet like?