Cervicogenic Headache

It occurs due to disease processes afflicting the joints of the upper neck region (cervical region). Classically, the resulting pain in the back of head is often one sided but can have variable presentation.

Previous injury to the neck region and old age are important risk factors. Precipitating factors include neck movements and prolonged uncomfortable postures.

Occipital Neuralgia

Probably a "seizure" that is localized to the nerve innervating the back of head.

This "seizure" results in severe pain at the back of head in the area supplied by the affected nerve.

Brain Tumors

Pain in back of head can occur. Other symptoms include vision problem, personality changes, hard to keep balance, etc. 

Cancer Metastasis to Skull

Spread of cancer to the base of the skull (occipital bone). Primary cancer can be anywhere (prostate, lung, breast, etc).

Severe pain at the back of head results from the invasion of cancer in occipital bone. Headache is followed by difficulty in swallowing and speaking (after few weeks).

Lateral Atlanto-axial joint disease

Most commonly due to rheumatoid arthritis. Affliction of this joint causes irritation of the spinal nerve originating at this level. It results in severe pain in the back of head and neck.

Radiculopathies

Radiculopathies refer to compression of the nerve roots as they exit the spinal cord. Compression often caused by an artery and results in persistent pain in the back of head.

Dialysis Headache

Headache is a common complication of dialysis. Nearly 1 out of 4 such headache occurs in the occipital region (back of head).

Orgasmic Headache

Rarely, orgasms can result in headache due to constriction of blood vessels of the brain. People often experience pain in back of head, but pain can occur in whole head also.

Intracranial Hypertension

Raised intracranial pressure can result in throbbing headache localized to back of head. Headache can also occur in other regions.

Often there are numerous other associated symptoms like altered consciousness, behavioral changes, nausea and vomiting, seizures, double vision, weakness, etc.

Raised intracranial pressure can be caused by numerous conditions (brain tumor, head injury, stroke, meningitis, etc.)

Intracranial Hypotension

Pain can occur in the back of head, although most common location is the sides of head.

Pain is often exacerbated by sitting or standing and relieved by lying down. It commonly occurs after spinal anesthesia or lumbar puncture (spinal tap). Can occur spontaneously without any cause (Idiopathic Intracranial Hypotension)

Arnold-Chiari Malformation

A congenital malformation of the brain resulting in pain in the back of head. The headache is often provoked by exertion or coughing.

There can be other associated symptoms like muscle weakness of face and neck, nausea and vomiting, dizziness, difficulty in swallowing, etc.

Dengue Fever

This is a virus-caused disease that results in high grade fever, headache, muscle aches, joint aches, nausea and vomiting. Headache is usually behind the eyes, but in nearly 20% of the cases it occurs at the back of head.

Cluster Headache

Rarely, cluster headaches can be localized to the back of the head, although the most common location is around the eye. They are almost always one-sided.

The pain is of immense severity and considered to be one of the worst pains described.

Migraine

Rarely, migraine can present with pain in back of head, although more commonly the pain of migraine is located on one side of the head.

Migraine headache is usually associated with myriad of other symptoms, like stiff neck, sudden nausea, etc. 

Subarachnoid Hemorrhage

This causes sudden onset of very severe headache due to bleeding between brain and the tissue layer covering the brain.

The headache is typically located at the back of the head and often associated with other symptoms like stiff neck, nausea and vomiting, vision disturbances, confusion, irritability, etc.

Vertebral Artery Dissection

Very rare condition, which can cause sudden onset very severe headache at the back of head.

Temporal Arteritis

Inflammation of the blood vessels supplying the head area (especially side region) occurs in this condition.

One of the symptoms is throbbing headache in the back of the head. The headache can also occur on the side.

Temporal arteritis can result in numerous other symptoms like jaw pain, stiff neck, neck pain, blurred or double vision, fever, excessive sweating, muscle aches, etc.

Sleep Apnea

Sleep apnea frequently results in headache, which may occur exclusively in the back of head region.

Parkinson's Disease

This can have neck pain and pain in back of head.

Retropharyngeal Tendinitis

Very rare cause of severe pain at the back of head. Often associated with pain on swallowing.