i think that symptom is caused by a hyperawareness to any motion. when most people (meaning people without dp/dr) walk or drive their brains filter out most of the bumping and jolting so it mostly looks like a continuous motion...when some of us walk or drive, we "notice" that we are bobbing up and down and it can become very disorienting. its the same reason sounds are really loud sometimes or things look extremely detailed. just try to think about other things when you are walking or driving. distract yourself...at least that's what i do.