“What kind of medical problem could this have been?”

Over 40 years ago when I was 12 I had an inflammation of some sort that my mother refused to take me to the doctor for. I've always been curious what it may have been.

I was a virgin at the time and had started my period about a year earlier. The symptoms were discharge that would leave a beige crust over my entire crotch, butt, and underwear. I do not remember it having any odor. It was extremely itchy. We had Desitin in the house so I tried to self-treat with that but I don't remember if it helped much. It lasted several months (4 - 6?) before clearing up. It never recurred. I assume it is the cause of vaginal scarring that was discovered by an OB-GYN years later since I'd never been pregnant or suffered sexual trauma.

Any ideas or theories?