What Causes Red Colored Lump On The Pelvic Area?

I am a 36 yr old female. About 2 months ago I have noticed a lump in my left pelvic area between my hairline and the lips. I was told it should go away. Now the appearance is a reddish-purple color and about the size of a nickel and its flat. When I push on it to see how big it really is it seems about the size of pencil eraser and deeper than just surface. I havent been sexually actice since 2005 fyi. How concerned should I be?