Suggest Treatment For Sore & Tender Shoulder Muscles

My wife has been suffering for four days sore muscles in her right shoulder. Muscles are tender starting at her coller bone and extending to shoulder blade. She started with a patch of rough skin about one quarter inch wide by about one inch long, with very tiny bumps slightly lighter than the surrounding skin.. Now two day later she has another just like it. It look like some of the milder cases of contact dermatitis I have looked at, but what about the muscle pain....