Now this question I'm about to ask right now is very important because it might get rid of this fear once and for all or at least reduce it significantly.

The question is that even though we cannot sense constant motion in that our bodies cannot detect it, can we feel constant motion in our own heads through thought or visualizing something (as an example given here):

Even though this person is not receiving any movement signals from the body, he/she feels that he/she is moving just from visualizing the stars. Is this feeling of movement a feeling of acceleration in his/her head, or is it an actual feeling of constant motion achieved in his/her own head?

But aren't our brains only designed to feel acceleration, therefore, making it impossible for our brains to even feel constant motion through thought or visualization?

The reason I ask this is because my fear of feeling that I am in constant motion from knowing that the Earth is in constant motion makes me feel like I am moving in constant motion. But is this feeling of constant motion I am experiencing not a feeling of constant motion at all and is instead a feeling of acceleration and that my mind is mistaking this feeling of acceleration as a feeling of constant motion (since, again, aren't our brains only designed to feel acceleration)?

If this feeling I am experiencing in my own head is a feeling of acceleration, then that means I have no reason to fear because of the fact that there is no acceleration which makes that feeling completely false. But if this feeling I am experiencing in my own head is indeed a feeling of constant motion, then that means that this feeling (even though it is a feeling obtained by thought and not obtained by the body) is true because it's true that the Earth is moving in constant motion.

Could someone who knows how the brain works answer this question for me and show me links to information that backs up his/her answer?