A young male patient comes into the office complaining of so…

A young male patient comes into the office complaining of sores in his mouth and on his lip. He has never had a cold sore before. He has been taking a sulfonamide drug and noticed the lesions shortly after he began taking the medication. You notice multiple lesions on his fingers as well that are “bulls eye” in shape. His lips are crusted and bloody. Based on this information, what do you think the patient may have?