This Is Very Awkward, So I'll Try To Keep This

This is very awkward, so I'll try to keep this very short and to the point.

I'm a 17 year old virgin, so I know this isn't sex related. What could cause bruise like discoloration on the outer most part of a vagina?

Thanks for any help in advance and I'm so sorry for this awkward question but I'm mildly concerned.