I've got a strange, hard and movable lump on my collar bone, please help so WORRIED!?

Hi im 14 and about 3 - 4 days ago i realised a small bone like lump which can be moved just bellow my collar bone which can only be felt and seen if i push the muscle up so that the lump is laying on or above my collard bone, please, if somebody could tell me what it is or maybe even just slight clue to what it is, and if it's something to be worried about or not, the lump hasn't caused any pain but i only realised it when i was led in bed and it felt like something was scratching my collard bone so when i put my hand over it to feel it there was a small lump probably about 3/4 of the size of a 5 pence coin, and i have thought about the possibility of cancer, as i don't know much about cancer could someone please tell me if sometypes are curable or not it would be allot of help, thanks...