I am a 21 year old female, 7 1/2 months postpartum. The last few weeks I have experienced a sudden onset of motion sickness when riding in the back seat of my car. I have experienced motion sickness my whole life, but usually only while reading, doing crosswords, etc. in a moving vehicle. However, the bouts I have experienced lately have come on suddenly for no apparent reason. I also just felt really weak, nauseous, light headed, etc, just now laying in bed, which is exactly how I feel when experiencing motion sickness in the car. I have no idea what could be causing it. Help?