If I remember right (and that is sometimes difficult for me) , we have had a similar thread a couple of times in the past.
For me, over the last half century, the creaking and popping noises in my neck and back and elsewhere were the sounds of fusing being diverted. I have kept straining my neck by turning my head from one side to another and I do it every day and sometimes twice or more a day. While it makes a lot of noise, the repeated movement to each side does give me an increased angle of possible neck movement and I have slowed down and essentially stopped my neck from fusing and keeping my head in a fixed position.
The noise is a sign of the start of fusing but more so, it is the sound of delaying the fusing.
We have in the past, joked about getting a group of AS sufferers together and forming a musical band with our various expertise in making these creaks and pops and whatever noise we can possibly manage. Hey, you gotta make your fun someway.
George
Breb Assyl