Is your chiro doing the Twist the head and pop the neck, adjustment ? This can be too aggressive for many. Even range of motion exercises can be a strain.

I was a mess from T-4 up. Chiro helped some but PT who uses myofacial release did the most for me. The muscles that were spasming in my upper back and neck needed to be calmed down. My chiro diagnosed TOS (Thoracic Outlet Syndrome) and sent me looking for a PT who knew how to treat TOS.

There is an X-ray set than can help. Some of us have cervical or false ribs at the bottom cervical vertebra. They can cause inflammation and spasming and TOS. I have them. Targeting them changed my life. I also did a lot of icing to reduce the inflammation. I took anti-inflammatory meds daily (enteric aspirin works great)

The most important thing was changing my sleep posture. When I sleep with good head and neck posture, I sleep better and wake refreshed. It takes months of good sleep posture for the ligaments to stabilize the vertebra. In the beginning, I spent many nights sleeping in a recliner. An adjustable bed that helps one sleep straight on their back can do the same.

My wife noticed that when I fell asleep in my recliner, my breathing improved and the expression on my face was peaceful. When I was in bed, I would have odd breathing and maybe a grimace on my face. She could tell how my day was going to be by observing my breathing and facial expression.

I finally learned how to sleep in bed in a good posture.

Hope you can find the solution to your neck.

My best to you.