Approximately one and a half year ago an unusual bruise showed up on my back, around the waist area. I didn't hit anything, it just showed up. Its about the size of a lemon. Since then, the bruise didn't go away and sometimes it itches, some sometimes I have a burning sensation (from inside out) and sometimes the area hurst (inside, not superficially). Has anyone experienced that? Should I be more concerned than just investigating the causes?