Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Those aren t typical side effects of Postinor-2, but it s possible to have been from that medication. It s a high dose of progestin (like the hormone of pregnancy) and can cause a number of side effects. Her risk of pregnancy from this episode is extremely low both because of no semen in the vagina, and because of the Postinor taken immediately. Also, those aren t typical early signs of pregnancy which are mostly fatigue and breast tenderness (which can be from Postinor also!). Here is what I recommend: if her headaches and abdominal pain are severe or increasing, or if there is any fever, then she should go in to be seen and examined in person as the cause may be something else - other than Postinor. Infections, appendicitis, and other causes can create abdominal pain. If there is nothing else going on, she may have to wait out the effects of the Postinor which can screw up the hormonal cycle in general, which may possibly be what is going on. Some women have their hormones thrown off for the entire cycle because the high dose of progestin (even though it is by now out of her system) can interfere with ovulation in a way that makes the rest of the month atypical. You and she may want to consider a regular form of birth control such as the Pill (which is a low steady dose of hormones rather than a sudden hit of high hormones) or IUD or condoms + spermicidal jelly. Of these, the IUD like Mirena is most effective, then the Pill, then condoms + spermicide. There are other contraceptive options too. Hope I have answered your query. Let me know if I can assist you further.