Burst vein in breast.

Hannah • Texas wife to my Taylor and mama to my sweet boy Easton, and a bull terrier- Lucy. We have #2 coming Feb 2017!
I noticed a vein in my breast was very large and noticeable, and the next day it was a bruise, like it burst. Few days later, the bruise is almost black. About the size of a nickel. Does this happen to anyone else?