There is an old post on bacterial vaginosis, you can use the search box to read about it. But let me reply to this, bacterial vaginosis occur when there is a change in the natural balance of bacteria in the vagina. When a certain bacteria becomes too much, it leads to a change in color, texture and odor of the vagina.
Discharge and color may be in form of a thin white, grey, or green discharge, and a fishy smell. Women experiencing BV can have itchy vagina, and burning sensation when urinating.
Treatment may include vaginal probiotic supplement to balance the pH of the vagina, but most importantly, see a doctor for proper treatment. A new partner or multiple sexual partners can increase your risk, so make sure you use condoms.