This headache is generally relieved on standing (consistent with raised intracranial pressure). It is aggravated by straining,
coughing or a change in position. This
headache is accompanied by various neurological symptoms such as dizziness, numbness, loss of vision, loss of hearing etc, all of which are temporary.
You can consult the neurologist regarding this. Hypothyroidism, hypoparathyroidism, adrenal insufficiency are a few things I would recommend your brother gets investigated for.