Hmmm...my wife usually gets the headaches and upset stomache instead of making love, not afterwards!

Ok, here's my idea. Try having him wear a condom. If you still get the symptoms, then you can rule out a semenal allergy or a reaction to any medication that could be being passed along to you in his fluid. Perhaps your orgasm is triggering some chemical/hormonal release that makes you feel like crap?

__________________
Though I am different from you,
We were born involved in one another.

For it was not into my ear you whispered, but into my heart. It was not my lips you kissed, but my soul.

Complete surrender should not just come at moments in which one faces overwhelming odds, but in the calm when it seems one is personally in complete control of one's life.