A 74-year-old man presents with a history of increasing frequency of headaches, fatigue, and weight loss for 3 months. He has had migraine headaches in the past, but these are different from them. He is also experiencing back, shoulder, and hip discomfort, which is worse in the morning. His head and neck examination is normal. Range of motion in the shoulders and hips is reduced because of discomfort but there is no active inflammation. Which of the following signs or symptoms is most helpful in the diagnosis?