I have a horizontal purple line right below my right chest that comes and goes throughout the day. When I wake up in the morning it's barely visible but by the end of the day it's as dark purple as can be. this first showed up 2 years ago after a night of consuming too much alcohol and bumping that part of the body directly into the side of a piece of furniture. What is most likely causing this, as it dos not look appealing, but is never there in the mornings?