Final answer:
The patient's symptoms and medical history suggest possible CNS involvement, further evaluation and imaging studies should be done to confirm the diagnosis of brain metastasis or other CNS involvement.
Step-by-step explanation:
The patient's symptoms of headache and fatigue, along with their medical history of metastatic melanoma and treatment with nivolumab, suggest a possible diagnosis of central nervous system (CNS) involvement. It is important to consider the possibility of brain metastasis, which can cause symptoms such as headache and fatigue. Brain metastases are a common complication of melanoma, and nivolumab, as an immunotherapy drug, may have an impact on the CNS.
To confirm the diagnosis, further evaluation and imaging studies should be performed, such as a brain MRI or CT scan. These tests can help identify the presence of brain metastasis or any other CNS involvement. The patient should consult with their healthcare provider for a proper evaluation and management of their symptoms.