Irregular Chest Pain. Could help myself.

I am a 15 year old girl. I work out often and drink lots of water each day. About 6 months ago I would drink a bottle of water maybe once a week. Sometime less. I've been having chest problems for about two years now. Sometimes my whole chest has sharp pain, others, like right now, it hurts on one side of my chest. Right now there's dull pain right below my left breast. Just a few minutes ago it was sharp but not extremely painful. It feels like if I stretched it would hurt, but It is actually not painful. I don't know if I'm explaining this well enough for anyone to know what's wrong. But my family can't really afford for a check up. I would just like to know if there are any other ways I could help myself.