What Causes Brown Spots Between Labia Majora And Minora?

What small brown spots are something to get checked? Hello there i have a friend that only trusts me to talk to about her personal things like this. She says that she has this brownish spot between the labia minora and majora and has had this for a while, though only recently has it given her any trouble. She is sexually active and so the last time she had done it with her boyfriend, the rubbing on it was giving her grief as she put it, and right afterwards she said it was a bit tender. It isn t really a lump, bump, or anything protruding, nor pus, but it is worrisome at the least to her. I tried to help her out, but everything on our internet search made her worrying worse. She d like to know if this is anything to truly worry about.