For about a week now i've had a nasty pain in my upper left back, under my shoulder blade. It doesn't feel like a pulled muscle or anything, as it hasn't improved at all. I'm worried it might be referred pain from something else? My left bottom of ribs has been feeling tender for a few weeks now, almost like a stitch when I move or breathe in too deeply. Should I go to the doc, or am I being over anxious about normal aches and pains?