A 70-year-old woman is seen by her physician for evaluation of severe headaches. She noted these several weeks ago, and they have been getting worse. Although she has not had any visual aura but she has been intermittently losing vision in her left eye for the last few days. She denies new weakness or numbness, but she does repo jaw pain with eating. Her past medical history includes coronary aery disease requiring a bypass grafting 10 years prior, diabetes mellitus, hyperlipidaemia, and mild depression. Full review of symptoms is notable for night sweats and mild low back pain paicularly prominent in the morning. Which of the following is the next most appropriate step?