Weird pebble feeling-bump/mole on my lower back?

Ok for like a year now i have had this painless little redish/slightly pinker than the rest of my skin bump. It feels like a little pebble or rock is directly under the skin. It doesnt itch or hurt and i doubt its a pimple because it has no white head (and its been there a year!) Im not really sure if it is a mole...i have hardly any moles on my body. I'm worried though that it could be melanoma because i did tan alot 3 years ago. It is a perfect circle though not ymetrical or anything.