After my boyfriend finishes inside me i feel nauseous i even feel like vomiting at times i currently have an iud could it be serious? spotting monthly

Worth a visit: It seems unlikely this has anything to do with something bad, but it may be worth a visit with your doc. Nausea only related to "finishing in you " may be more a fear of BC failure than a true medical problem, but a review of your present method may end that problem.

Seminal allergy: You may be allergic to seminal fluid leading to an anaphylactic reaction for which an allergist should be consulted. A less likely scenario is migraine from intercourse.