It started around two months ago on one side underneath my arm - felt itchy but not scratch-able, the skin was just irritated and sore to the touch and felt swollen, and the muscles felt achy as well. Now it's gone up my shoulder and the side of my neck. There is no visible rash but it feels like one (but when I go to scratch it, it's not satisfying, just feels irritated), and my muscles and joints on that side are extremely uncomfortable. The side of my neck is now painful as well.