A 'cervical' pillow is meaningless if it does not fit your neck properly And if you change positions during sleep.

There is a motion x-ray that can see if the cervical vertebra are stable during movement. A static x-ray would just show poor position.

There are 2 impulse machines I am aware of. One is hand held. It is called the Activator. The other is a fixed machine with an arm that impacts the vertebra. Atlas orthogonal chiros sometimes use the latter.

The stem cell injections can be fabulous in the right hands. There are some who oversell and under perform.

Prolotherapy can also help at much lower cost and less risk.

It will be difficult to get improvement unless you can find a way to be stable during sleep. In my opinion, it is better to spend a few months sleeping flat on your back in a recliner or adjustable bed where you cannot roll over and change positions before spending the big bucks. I just lay my head back and find a position where I have to sense of discomfort. I use a pillow that I can shape to support my head so it does not roll right or left.

A physical therapist who can help with gentle traction and manual mobilization without attempting to force vertebra movement can be worthwhile. Frequent icing will also help. Inflammation is a big problem and needs to be addressed.

I've tried the chiro ( a chiro who had been successful with many other vertebra issues using the Activator for 15 years) and he realized my neck needed longer term healing with more a gentle approach.