I think i have Fecal body odor

Ever since 9th grade iv been smelling like fart and poop.im in 10th grade now. im tired of it. it only happens in school and rarely at my house and other places. it makes me nervous all the time. its hard to concentrate on school cuz i always think about if im smelling or not. sometimes the smell comes and goes. im going soon to see my physician and tell him about. if u have have advice PLEASE TELL ME! im not sure but i think i have fecal body odor. i need something that will get rid of it. i read other articles about diets but i dont think it will help. i saw an oxy powder cleanse think. not sure if that will work. PLEASE HELP ME!!!!