What Causes A Bony Bump On The Clavicle Bone?

Hello, I m a 22 year old female, 5 5 , 125#. Within the past few months I discovered a hard, immovable bump on top of one of my clavicle bones. It feels as if it is made of bone, is roughly the circumference of a penny with smooth edges and is slightly painful upon palpation (the pain is similar to pain I felt when palpating shin splints I had in high school as a runner). The edges of this bump are smooth, and the bump feels attached to the bone. I have never received an injury to my collarbone or anywhere on my upper body. I was wondering if this could be a possible bone spur? Are there any suggestions as to what this may be?