I am 16 years old, and i have a little sore lump above my left nipple. should i be concerned?

Maybe: This could be anything from a small sebaceous cyst to a fatty growth to an abscess. It's certainly hard to say much without seeing it and examining you carefully. If you don't have a fever, overlying redness of the skin or extreme pain with palpation, its probably ok to give it a couple days and see if it resolves on its own. If it doesn't resolve on its own within a week, get it checked!