Is this new? Then maybe an infection. If it is not new, there is a rare condition where a hole is between the colon and the vagina. But obviously if you had that, it would have been with you a while. Go to a doctor and get swabbed for B.V. It is one of the infections that can be characterized by a horrible smell. Oh, another possibility -- a forgotten tampon. Women write that those smell like rotten meat. Doctor can help you with that one too, don't be embarrassed, go. He or she has seen it all before.
Wiping from back to front can smear fecal matter into the vagina, and can cause infections. Wipe from front to back. Make sure you clean the area with gentle soap at least every other day, but preferably every day. Do not use perfume products. If it's actually your vagina, and it doesn't get better from washing plenty, then you might have an infection of some sort and should see a doctor.