Hi!!
If you aren't the one driving and its the bumps that bother you.... What I used to do before I was even driving, I would have my parents put pillows down behind my back, under my legs, and feet and anywhere to almost act like shock absorbers... NOW, if you have to be the one driving, I (if I really don't feel good but still have to drive) put a pillow under my butt and take frequent stops to just get out of the car or just to rest my feet and not have to keep using my foot. (mine is my right leg so pushing on the brake and gas hurts on a bad day)...
BUT I hope that is at some point to help someone