What Causes Light Pain In Upper Chest Area And Pressure On Left Arm?

Hi, I m a little concerned. My upper chest area above my left breast well it seems to feel like light pain. and when I put pressure on my left arm, my left side of my upper chest will hurt, when I Exercise and moving my upper body I feel it start to hurt. and when I lay down my upper chest will hurt with Icy Hot it seems to feel a little better. Is it something minor that I can take care of myself? or anything I can use or take for it? Did I pull a muscle? Thank You