What Causes Pigmentation Between Vagina And Anus?

Dear Doctors, I am a 27 year old female; my height is 170cm and my weight is 74Kgs. I used to have cottage like discharge and scented urine but i no longer suffer from that. Still my urine smells a little funny sometimes but no discharge issues. But my current problem is that i just noticed a big white crescent shape pigmentation between my vagina and anus is that something that should worry me. FYI my ex bf had a white pigmentation on hill testicles too. Is that something I caught from him?