I don't know if this is the correct answer, but maybe the stuff I remember from having a bodybuilder ex-boyfriend might be useful?
Do you think you got your blood pressure up too much when you were in the weight room? Mister X always had to be careful about how intensely he worked for how long, because that was something he had done in the past. And he didn't act like it was a pleasant thing.
I found this article (Exercise Induced Nausea), which basically says what I remember my ex saying, but this sentence at the end struck me a little.Do you think that's a possibility?If, as a weight lifter, you consistently experience post-workout nausea, remember that dehydration and (ironically) over-hydration or water intoxication can manifest itself as nausea after exercise.
I've got no advice, since I'm no guru, but if it were me, I'd see my doctor if it happens repeatedly. That just doesn't sound right.