Pain in between breasts?

I am a teenage girl and I have had a pain in between my breasts (upper sternum area) for about a week now. It's only painful when I touch it, and when I do it feels almost like a sharp bruise. I haven't bumped it on anything, and there's no bruise or mark, but it's starting to worry me. It is not on either of my breasts, just right in between. Is this something I should get checked out?