Dark spot around my mouth?

I am a brown-skinned female and I have a pretty nice skin complexion with the exception of a dark, blemish-like, spot like around my mouth area. It makes it look like I have a mustache. Maybe I am looking to much in my face. I have asked beauty consultants and they say it doesn't look like that. I am very self-conscious about it. I don't wear make-up (well---I wear lipstick). I know I can cover it up with foundation, but I do not want to depend on it. Is there a cream or some type of remedy to lighten it?