Body feels heavy, with stiffness of neck and back of head. usually in the later part of day and worse while standing ?

These are vague: and not uncommon symptoms. They are also very non-specific. Heaviness and stiffness generally suggest some dysfunction of connective tissues: muscles, joints, tissues that connect. It can be simple fatigue, but bony degeneration, muscle spasm and even injury can be the cause. These symptoms are often associated with stress as well. Try relaxing: deep breathing, meditation, massage. Ice/heat.