Practice question

A 65-year-old woman presents with a 3-week history of new-onset pain and stiffness affecting both her shoulders and hips. The stiffness is particularly severe in the mornings, lasting over an hour, making it difficult for her to get dressed or lift her arms. She also reports feeling generally unwell and fatigued. Her Erythrocyte Sedimentation Rate (ESR) is elevated at 75 mm/hr. What is the most likely diagnosis?