Tension headache: This is the most common type of headache and is often described as a band or a squeezing sensation around the forehead, usually accompanied by muscle tension in the neck and scalp. The duration of one week fits within the typical timeframe for tension headaches, which can be episodic or chronic.

Migraine: Although migraines are typically episodic, some individuals may experience prolonged or frequent episodes that could last up to a week. Migraines are characterized by severe, unilateral pain, often accompanied by nausea, vomiting, and sensitivity to light and sound.
Sinusitis: Inflammation of the sinuses can cause headache, particularly in the frontal and facial areas, and can last for several days to over a week. Other symptoms include nasal congestion, facial pain, and purulent nasal discharge.
Cluster headache: While cluster headaches are typically very short-lived, they can occur in clusters or cycles that might last for weeks. These headaches are extremely painful, usually unilateral, and centered around one eye.

Subarachnoid hemorrhage: Although less common, a subarachnoid hemorrhage can present with a sudden, severe headache (often described as "the worst headache of my life") and can sometimes have a more prolonged course if there is a slow leak. It's crucial to consider this diagnosis due to its high morbidity and mortality.
Meningitis: Infection of the meninges can cause severe headache, fever, neck stiffness, and altered mental status. The duration can vary, and it's essential to diagnose promptly due to the risk of serious complications.
Temporal arteritis (Giant Cell Arteritis): This condition, more common in older adults, can cause headache, usually unilateral and temporal, along with jaw claudication and visual disturbances. Missing this diagnosis can lead to blindness.
Brain tumor: Although rare, a brain tumor can cause headache, often worse in the morning and improving throughout the day, due to increased intracranial pressure. Other symptoms might include seizures, focal neurological deficits, and changes in mental status.

Idiopathic intracranial hypertension (IIH): Characterized by increased intracranial pressure without a detectable cause, leading to headache, vision changes, and sometimes papilledema. The headache is often worse in the morning and can be accompanied by transient visual obscurations.
Cervicogenic headache: Originating from the cervical spine, these headaches are typically unilateral and can be accompanied by neck pain and limited range of motion.
Trigeminal neuralgia: Although more commonly presenting with facial pain, in some cases, it can manifest as headache, characterized by intense, shock-like or stabbing pain in the distribution of the trigeminal nerve.