Tension Headache: This is the most common type of headache and often presents with bilateral occipital pain, which can be attributed to muscle tension in the neck and scalp. The reoccurring nature and location of the headache make tension headache a plausible diagnosis.

Cervicogenic Headache: Originating from the cervical spine, this type of headache is referred to the occipital region due to the convergence of cervical and trigeminal nerves. It is often associated with neck movements or trauma.
Migraine: Although migraines typically present with unilateral pain, they can sometimes be bilateral and may involve the occipital region. The reoccurring nature could suggest a migraine pattern, especially if accompanied by other migraine symptoms like aura, nausea, or sensitivity to light and sound.
Occipital Neuralgia: Characterized by sharp, stabbing pain in the occipital region, this condition involves the irritation of the occipital nerves. It can be recurrent and may be triggered by specific movements or pressure on the nerves.

Subarachnoid Hemorrhage: Although rare, a sudden, severe headache (often described as "the worst headache of my life") could indicate a subarachnoid hemorrhage, which is a life-threatening condition requiring immediate medical attention. The occipital location might not be typical, but the severity and sudden onset are red flags.
Meningitis: Inflammation of the protective membranes covering the brain and spinal cord, meningitis can cause severe headache, including in the occipital region, along with fever, neck stiffness, and altered consciousness. It is a medical emergency.
Giant Cell Arteritis: This condition, more common in older adults, involves inflammation of the blood vessels and can cause headaches, including in the occipital region, along with jaw claudication and visual disturbances. It is a medical emergency due to the risk of blindness.

Chiari Malformation: A structural defect in the cerebellum that controls balance, Chiari malformation can cause headaches, often occipital, due to the compression of the cerebellum into the spinal canal. Symptoms can worsen with coughing, sneezing, or straining.
Eagle Syndrome: Characterized by an elongated styloid process or calcified stylohyoid ligament, Eagle syndrome can cause sharp, stabbing pain in the side of the face and the occipital region, often exacerbated by swallowing.
Atlantoaxial Subluxation: Instability or misalignment of the joints between the first and second cervical vertebrae can cause occipital headaches due to the compression or irritation of the nerves and blood vessels in the area.