b) Assess the adolescent's vital signs and respiratory rate.
When a patient reports a sudden increase in pain to the maximum level on a pain scale, especially after receiving pain medication, it is essential for the nurse to assess the patient's vital signs and respiratory rate. This is because severe pain can sometimes indicate a complication or adverse reaction to the medication, such as respiratory depression. Assessing vital signs and respiratory rate will help the nurse determine if there is any cause for concern and if further intervention or consultation with the healthcare provider is necessary.