Response to the pain medication

The second shift nurse is taking a report from the first shift nurse, whose behavior has changed in the past few weeks. Other nurses have commented that the first shift nurse has had a lot of stress at home. The first shift nurse reports that Mrs. M. just received an intramuscular injection of 8 mg of morphine 20 minutes ago, and he has not had time to assess Mrs. M.’s response to the pain medication. The second shift nurse assesses Mrs. M., who states, “It has not helped my pain at all.” How should the nurse manage this situation?