What Causes A White Spot On The Vaginal Lip?

Hello. This is embrassing but when I went to the bathroom yesterday I thought I wiped to hard. And like 2 mins later something was like hurting on my vagina so I grabbed a mirroed to see what was going on and I noticed a flat white little spot on the right lip of my vagina kinda towards the middle. So I put vasaline on it. It doesn't burn when I pee or anything. So I was wondering what it could be I'm am really worried. I am 18 years old. Please help!