The concept of leaning your head against the wall can be a problem in itself. If this means you have your head propped up and forward, this can put a strain on the joint between the neck and skull. The inflammation from the strain can cause symptoms. Add a startle from somebody slamming the door and the brain chemistry goes sideways.

The biggest point about the neck is avoiding these bad postures and sleeping or resting in a good straight head and neck posture, ALL THE TIME. Doing it most of the time does not help much because the bad times still cause the inflammation.

If a car ride is bumpy, lean forward with your shoulders and head. This adds curve to your back so you can absorb the vibrations better. When you shoulders are against the seat back, the vibrations are stronger.

I also take 975 mgs of enteric aspirin morning and night.

A chiro or PT or osteopath who has gentle neck techniques for getting the joints moving can also help. No chiro 'turn the head and pop the neck' for most of us. It is too aggressive.