I have the exact same experience. I believe it's called "somatic tinnitus" and I've had it for as long as I can remember.
Every now and then I get ringing in my ears that fade out quickly, which is normal. I always thought that was the sort of constant ringing people had when they talk about tinnitus, and the one you describe is a different class of tinnitus.
Yes it's somatic tinnitus. I can make mine go away for a few hours, sometimes a whole day by loosening up my SCM muscles and popping my neck. Other times it backfires and gets worse. Very annoying, but the ability to have SOME control over it makes things less depressing at least.
Every now and then I get ringing in my ears that fade out quickly, which is normal. I always thought that was the sort of constant ringing people had when they talk about tinnitus, and the one you describe is a different class of tinnitus.