A 72-year-old man presented with a 4-day history of vague tingling over the upper right side
of his face.
On waking up that morning, a vesicular rash had developed over his upper right face,
including the tip of his nose, and he noticed that his right eye was watering. He had a history
of lichen planus, and for the past 3 years, he had used topical tacrolimus to treat it.

What is the most appropriate next step?