We need more information. Is it internal (inside), external (outside), or both? Have you had sex recently (around the time of this beginning?) I suspect it may be bacterial vaginosis. If you've had sex recently that could change your pH balance, make BV more likely, or it could mean a sexually transmitted infection.
If you can, I suggest seeing a doctor about it. Even just calling a doctor's office, and talking to them over the phone. They may be able to help you figure it out.