Which of the following is important to determine in the recent history of a child with suspected Clostridium difficile infection?

Mark is a 15-year-old with complaint of acute left scrotal pain with nausea. The pain began approximately 6 hours ago as a dull ache and has gradually worsened to where he can no longer stand without doubling over. He is afebrile and in marked pain. Physical exam is negative except for elevation of the left testicle, diffuse scrotal edema, and the presence of a blue dot sign.