Seen in the ED: Vertigo and Ear Pain in an Older Woman

The woman's symptoms have been progressively worsening over 4 days; there is no facial weakness. Will the external ear findings lead you to a diagnosis?

History of present illness

A woman her 60s with a history of diabetes presents to an urgent care center complaining of 4 days of progressive left ear pain, nausea, and dizziness. She denies any facial weakness or other complaints.

Vital signs & physical examination

Vital signs are normal. Physical examination is otherwise normal except for right beating nystagmus on rightward gaze, mild left facial weakness not noticed by patient, and the external ear finding shown below.

What is the most likely diagnosis?