What Does Pain In The Upper Back Indicate?

For the last 7-10 days, I have had pain in the upper left portion of my back, like a pulled muscle. I keep taking Bayer Back and Body at night because I can't sleep unless I do. Then, about 4 days ago, the same area started itching; I thought it was dry skin from heating the house for the winter. I asked my husband to put hand lotion on my back, and he said, "Oh, my God! You have two huge whelps on your back and a bunch of smaller red dots to the left. The pain that has come with it is like a sunburn.