Ben,

We have told you many times that anxiety can be causing these roller coaster symptoms.

Yes, if nobody else is effected by the bouncing, it should not be effected you.

As I said before, if the road is rough, do not sit with your shoulders and head against the seat back. Hold you shoulders and head forward like you are reading a book in your lap. This will make your spine much more flexible so the bouncing is easier to tolerate.