**Core Concept**
The patient's presentation is suggestive of a non-traumatic subarachnoid hemorrhage (SAH), which is a life-threatening condition that requires immediate attention. SAH is typically caused by the rupture of an aneurysm or arteriovenous malformation (AVM) in the brain.

**Why the Correct Answer is Right**
Subarachnoid hemorrhage is characterized by the sudden onset of severe headache, often described as "the worst headache of my life." This is due to the accumulation of blood in the subarachnoid space, which irritates the meninges and causes severe pain. The patient's NCCT (non-contrast computed tomography) scan would show blood in the subarachnoid space, confirming the diagnosis. The underlying mechanism involves the rupture of an aneurysm or AVM, leading to bleeding into the subarachnoid space.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as SAH typically presents with a sudden, severe headache, not a gradual worsening of symptoms.
**Option B:** This option is incorrect as SAH often presents with nausea and vomiting, but not typically with a history of fever.
**Option C:** This option is incorrect as SAH is often associated with a loss of consciousness, but not typically with a history of seizures.

**Clinical Pearl / High-Yield Fact**
In patients presenting with a sudden, severe headache, it is essential to consider SAH as a potential diagnosis, as prompt diagnosis and treatment can significantly improve outcomes.

**Correct Answer:** A.