What Could Hard Veins With Bruises In Breast Suggest?

About a week ago I noticed an area on my rib cage just under and to the outer side of my left breast that felt bruised. I don't recall bumping into anything, and there is no sign of bruising. However, three days ago I noticed what feels like a hard vein that I can feel running about three inches down. Now you can see it slighty protruding over my rib cage. I have never felt anything like this, and I am starting to get worried I have blood clot. I am a 27 y/o female and never had any major medical problems.