There are many different reasons as to why pain in the back of the head occurs. Arthritis, bad posture, spinal issues, neural symptoms, or headaches may all cause muscle pain to develop.
Arthritis can cause the surrounding muscles to become tight and tense. In turn, you may experience pain at the base of your skull and neck. Bad posture or a kinked neck can also place tension and stress on the muscles that attach at the back of the head. This can create pain, amongst other issues.
Any injuries or conditions involving the spine can cause muscle pain on the back of the head. Disc degeneration and a herniated disc can happen to the spine. In turn, tension may build in surrounding muscles and muscles that attach to the back of the skull. Neurological disorders, tension headaches, and migraines can also create muscle pain in the area.