I have also had this kind of vertigo or earthquake feeling from time to time for several years. It happens when I turn my head while walking or even when I sit still on a chair. Although a brief moment, it feels like the ground is moving. I usually cannot help but look around to see if other people feel the same or if they start to run out of the building.
I once read that this vertigo was due to lack of protein in brain and I believed it and made myself some meals rich in animal protein. I did not find it very helpful.
I think after rifing this has happened a lot less, especially in the past few weeks after I have been on the Doctrine full time. Yes the Doctrine, unbelievable, and more.