Motion Sickness Due To Sex?

Aundrea
I get motion sickness very, VERY easily. And I was wondering, does anyone else here also feel a bit sick after having sex?
It generally happens if I get up, get in the car, or move around too soon.
I also have a tendency to get lightheaded easily. Even without sex if I stand up too quickly I'll get light headed. Typically includes feeling weak momentarily, slight swaying/loss of balance, vision getting blurry/darkening slightly.
Figure it could be because the blood flow changing rapidly when going from one laying down to standing quickly.