@velvinyl,
the neck moves in six directions in three planes. We have two tiny joints at the side of each vertebra to help them move smoothly. A tight ligament, tendon or muscle can alter the balance and trap the vertebra into an such a slight off position that eventually it does show up on MRI as osteophytes (bone growth) or arthritis.
Sometimes we have an injury to a lower part of the body (like the knees) that alters the balance in the way we walk or stand. That imbalance affects the spine all the way up the spine.
Untreated, over time, those imbalances adjust the muscles to maintain the imbalance. That imbalance can become stable, but still may be pinching the nerves that exit the spine. In some positions you don't have the pinch.
My thoracic vertebra shift and hold slightly to the right which affects mainly the 4-5, 5-6 cervical vertebra, the ones that give a person the shoulder pain and burning you describe.
Chiropractics may not be an answer for you, but it is so easy to try. Some chiropractors are moving away from manual adjustments to mechanical means of adjusting. You might make sure their method is manual before scheduling.
While relief is immediate physical therapy and massage help maintain the adjustment.
If you ask a lot of questions, they'll tell you everything about what misalignments you have and what exercises help maintain balance.
I hope it works for you.