Painful Red Ear

What caused vesicles and erythema and swelling of left auricle in this HIV-positive patient?

This HIV-positive patient has a 1 day history of left ear pain, dizziness, and vomiting. He has unilateral nystagmus on rightward gaze and subtle weakness of the left side of the face. There is 1+ erythema and swelling of the entire left auricle with multiple areas of superficial vesicles.

What cause do you suspect?