Why does my elbow hurt by the slightest touch?

For example, if I put my elbow on the table I get such a shooting pain. Or if I put it on some angle while sitting and it touches anything, a pain starts. Sometimes randomly of touched. Sometimes it not even there. It's REALLY irritating! I'm only 14. I don't member Hitting it. Fact, I don't even think I hitted it. My mom said it's probably bruised. But it's not, t been like this for almost TWO YEARS NOW. I'm sick of this!!! Anybody have any ideas what it could be? And anyway to get rid of it. It's on my left elbow also. If you feel your elbow you somewhat have two bones or whatever, well it's like in the middle of it. Why? I heard it was fluide or whatever. Help anybody!(: thanks so much!