What Causes Irritation And Soreness In The Labia Minora?

hi i am thirteen years old and around 2 days ago my left labia minoria started to get really sore and it felt really rough when i wiped my vagina as if it was irritating the skin but there was no blood or anything. i thought it was just a little irritation but it hasnt gone away so i checked in a mirror with a torch and i cant see any sores but my left labia minoria is red and floppy. ive never had sex or used a tampon and there hasnt been any bleeding but i always have quite a lot of whiteish discharge and when i go to the toilet it smells a bit like sour cream. i have had my period for 3 years and it has been regular since the beginning and i am currently on Levlen ED because i get really bad period pain. im really embarrased to tell my mum about this so help would be appreciated