Hello, I Have Been Having A Strong Coming From My

Hello, I have been having a strong coming from my vagina for a week now. I looked online and tried the tampon soaked in Apple cider vinegar method. I left it in for a couple of hours. When I removed it there was a black spot on one side of tampon. And the smell subsided a little. But still smells. What should I do. What is the cause of black spot and smell.