What Causes Bump On Neck?

Hi I just finished my homework and about to go to bed when I did a little neck stretching to ease out neck strain when I noticed my neck hurting a bit and touched it i felt a small bump on my neck and and upper neck behind my ear... is that a vein?? Should I be concerned?????? please answeeer. i also have a habit of stretching my neck sometimes it make sound... I'm still young so I don't know....