Dam...Must be some good stuff,not normal though...You should check your blood sugar level,my wife is diabetic and she has the same problems with dizzies during sex.
Yes a light headed feeling is quite normal. You have blood rushing around to different places and getting a workout you may not be used to. Also be sure to pad the headboard before allowing your head to be rammed into it repeatedly.
Have you been drinking enough water? Sounds like it could simply be orthostatic hypotension, if you are a very active partner-especially if you are "on top." You may want to see your doctor-there could also be heart issues, congestive heart failure for instance.
LOL, if both of you are dizzy, then its the side effect of the drugs. Or you guys were spinning around while you were having sex. Now, getting light-headed after sex, that's understandable.