This stinging pain runs from underneath my left breast, out to the side, underneath my armpit and down my side, near the ribs and scapula. It is tender on the right side too, but only under the armpit and down to the side. The left is much worse than the right and there doesn't seem to be any breast pain on the right side. When I have a mammogram, the stinging pain that goes along with the compression is almost unbearable. I know most women feel discomfort, but this is ridiculous. I start to sweat the pain is so bad on the left side. Not so much on the right side. The sides of my legs, when I press on them, are sore too. What is this?