Why do we have shoulder and neck pain? There are a lot of reasons as to why we have chronic pain here.
Energetically we receive information before we process it on a conscious level. Physically the chest, shoulders, arms, rib cage, lungs, thoracic spine and heart are governed by the heart chakra. The neck, cervical spine and throat are governed by the throat chakra. These energy centers are highly sensitive to emotional upset and respond with a physical reaction such as tightening up and hurting.
On a energetic level chronic issues here are due to not feeling heard or comfortable expressing themselves. Perhaps we get upset and feel we can't talk about it or we may feel powerless or vulnerable to someone's energy or situation. We may be fearful of the future due to our past. We may choose to introvert our opinions and emotions and therefore close our throats and hearts and avoid pain or ridicule. We may have trouble loving or accepting love. This prevents us from owning our power and shining in our own truth and creativity. The energy flow in these meridians shuts down.
On a physical level over time, feeling this way and over all not feeling respected and understood can certainly develop a pattern of elevated shoulders, protracted head and rounded upper back. Why, because we are protecting our organs and hearts from pain. We close up in the front body to feel less vulnerable. Head forward in an attempt to be heard and a sense of eagerness for acknowledgement. This is all very subconscious and can be deeply rooted in our past.
This creates patterns of tight clenched muscles that inevitably get stuck to each other and your range of motion decreases as your chronic pain increases.
Take into consideration long term posture deviations and repetitive movements to exacerbate the issue implemented by deeply rooted energetic responses from your past.
So over time these issues may travel not only into your neck causing pain and fatigue, but also make it's way into your upper back, chest, down your arms and sides.