If you have a white like small mass and it's external it might not be a problem at all. I had that same thing occur to me during my pregnancy and the doctor at the OB/GYN clinic told me it was just cyst and I had nothing to worry about. I hope in your case it's the same, but if you have any type of itching, burning or discomfort I strongly suggest you see a doctor.
is it on the vagina or in the opening of the vagina??