I have having this issue for almost 2 years now. On the 1st day of my period and ONLY the 1st day i get this really bad burning feeling in the vaginal area. It feels as if there is acid down there. my Doc was stumpped but suggested Vasaline but it doesn't help. Another thing i've noticed is if im on a walk or doing phscial things like house work or doing active things at work, that same burning feeling acts up. 

any other day im fine its just that 1st day.   I've nevr had sex, and non of the women in my family had or has what i have.