Hello, caryopteris may be right. It could also maybe be an infection. Are u a virgin? If not it could be an STD as these can cause discharge/smell etc. i would get checked out by a gyno as soon as possible. Good luck n keep me posted n hope this helped a little.
It sounds like a passageway has formed between your rectum and vagina (rectovaginal fistula). You need to see a doctor.