Hi Mathew I also hear this cracking crackling when i move my head. it seems like its coming from my neck. the top back bone, cervical spine. but maybe it is my ears i can't tell. both of my ears have been ringing constantly for at least the past 10 years and it really seems like forever. i think i have menieres, i've had about 10 attacks where i lose balance completely, get vertigo, and can't stand from 4-19 hours. all of my attacks were from May 2015-May 2017. I haven't had a loss of balance or vertigo since then knock on wood but i did have one bad dizzy spell. and my ears have rang constantly. high pitched ringing.
did you ever find out anything about the sounds you hear when when you move your head/neck?