This sounds really serious. Try calling a planned parenthood or a clinic in your area and ask a doctor
about it annonymously. If it is poo you are at risk of getting some really bad urinary tract
infections and bladder infections. If it's serious you need to fix it right away because something really bad could be going on. Try not to feel embarassed. Doctors see all kinds of crazy things and they are in their profession to help people. It's out of your control and not your fault so there's no need to be embarassed.