I have a bump on my shin but im able to move it like its a piece of bone. Could this be a fracture? Although I don't ever remember hitting my shin.

Possible fracture. Usually you would remember a trauma to cause a fracture. It would be a good idea to have an ortho doc eval you.
Sesamoid bone. This an extra piece of bone that floats like a small island . This is normal and occurs in a small percentage of people. Show it your doctor at your next appointment but there is no reason to worry .