Hi About Two Weeks Ago (after Coaching My Son With

Hi about two weeks ago (after coaching my son with some hitting and pitching techniques) I developed some tenderness to my left anterior ribcage (from the edge of my ribs to about 3 inches below my left breast). It was tender to touch and to stretch. I assumed it was a muscle pull or something. Over the past 4-5 days I've noticed what I would describe as a vein which I can feel, extending from about 3 ribs below my left breast to the front edge of my rib cage and then stops. It doesn't hurt to touch but when I stretch back, reach up or take a deep breath (anything that stretches my rib cage) it causes tightness in that area and mild discomfort and I can visibly see a vein like structure. It appears to pull on my skin when I stretch and seems slightly wider at the edge of the rib cage. As stated, it doesn't hurt to touch now with no other noted signs or symtoms. I have a doctors appointment on Friday but I'm very concerned. Any ideas?