What Causes Black Bump Inside Vagina?

I'm 18 years old, 5'7, 9 1/2 stone.I felt an uncomfortable feeling down below so had a look. I've just noticed i have a smallish black spot/bump on the inside of my vagina, im very worried as i havent seem to notice it before. I'm seeing someone at the moment but we've never had unprotected sex. I was with my previous boyfriend for 10 months and i was on the pill but I hadn't noticed anything like this before but never felt the need to check and haven't been in physical contact with him for almost 7 months. Any ideas on what it could be?