A 67-year-old nontoxic appearing male patient with a history of coronary artery disease, hyperlipidemia, transient ischemic attack, gout, renal colic, and squamous cell carcinoma presents with concern for multiple new painful lesions on his body. The rash first appeared five months ago but disappeared for some time before reappearing. It has worsened over the past few weeks. He has pain, erythema, pruritus, and urticarial, blistering, crusted lesions. He has had clear drainage from ruptured blisters. His only recent change in medication is an increase in his allopurinol (initiated four months ago; increased three weeks ago). He has tried Benadryl and steroids with minimal relief and is quite frustrated as this is his fourth emergency department visit for this complaint.