What Is The Pain In Upper Portion Of Vagina Before Period Starts?

Hello doctor! I m 25 years old female,56 kg wieght,5'5 inch hieght.i hv a problem that feel and little pain and look like a small guilty on my virgin upper,sometimes left or left before the date of period for last 2 years ,i m a marriad women and i hv a baby of 3 years.Please advise me. Thank u