Women feeling nauseous after sex could be the symptom of an underlying medical condition. Here are the possible causes.
Could be Endometriosis: Endometriosis occurs when bits of the tissue that lines the uterus (endometrium) grow on other pelvic organs, such as the ovaries or fallopian tubes. Outside the uterus, endometrial tissue thickens and bleeds, just as the normal endometrium does during the menstrual cycle. Sex can cause nausea if it puts pressure on the tissue growing outside the womb.
Cervical Stimulation: Except during childbirth, the cervical is not open and is too small to be penetrated. However, the stimulation that occurs when a penis or other object rubs or pushes against the cervix is what causes a pleasurable sensation for some people. But for some, if the penetration is deep enough to stimulate the cervix (the mouth of your uterus) it may cause pain and nausea.
Sexual aversion disorder: It could be psychological too. you may have developed an aversion for sex for some reason, perhaps from your past. You need to be aware of this.
So to be your sexual life to strong and beautiful you must be alert of these symptoms and must consult a specialist for treatment.