Author | Brandon Hill, MD

Her headaches haven't improved with prednisone. It's not meningitis. Your tests show negative for vasculitis but positive for Lyme. Can you guess the diagnosis?

The patient is plagued by problems: Severe headaches, nausea, vomiting, a rash, chest and abdominal pains, and by the time she reaches a rheumatologist, periorbital edema and photophobia. Can you guess the cause?