A 40-year-old woman comes to the physician reporting she has pain in her entire body. She says that for a period of several years she has had pain and stiffness that predominantly affects her shoulders, upper back, hips, thighs and knees. She also reports that she has fatigue and an increased need for sleep, sometimes sleeping for 14 hours per day but it is of low quality. She also has cognitive slowing and feels that she is “not all there mentally”. Her pulse is 68/mm, blood pressure is 140/58mmHg, respirations are 14/mm and temperature is 37.2C (98.9’F). She has pain to palpation of her deltoids, trapezius, lattisimus dorsi and her quadriceps. She has no joint deformities nor joint swelling or redness.Which of the following is the most likely diagnosis?