Final answer:
The RN should call the healthcare provider for an additional order for pain management.
Step-by-step explanation:
The RN should take the action of calling the healthcare provider for an additional order for pain management (D). The patient initially reported a pain level of 8 and was prescribed an opioid to be given IM every 4 hours. However, the patient's pain level remains at 8 after two hours, which indicates that the current medication regimen is not effectively managing the pain. Therefore, the RN should consult with the healthcare provider to discuss the patient's continued pain and obtain a new order for pain management.