A 38-year-old woman presents with acute onset severe thyroid pain, fever, and dysphagia for 3 days. On examination, the thyroid is tender and enlarged. TSH is 0.2 mIU/L (low), free T4 is elevated at 28 pmol/L, and ESR is 95 mm/hr. Thyroid peroxidase (TPO) antibodies are negative. What is the most appropriate next step in management?