What causes a sore scalp for years with no bumps or rashes and no flakiness and no swelling.

Scalp Soreness: Soreness of the scalp can be caused by a number of conditions and diseases. A simple tension headache can make the scalp feel uncomfortable. Occasionally, a fungus such as ringworm or parasites such as head lice cause the scalp to become sore. Rarely, scalp soreness is caused by chronic conditions, illnesses or autoimmune disorders.