welcome and thanks for posting your query to HCM.
Let me first reassure you that there is neither any chance of pregnancy
nor does the abdominal cramps are any sign of pregnancy.
Let me explain the reason. The best of the reason is you have had sex after 3 days of placebo tablets that means around 24th day of cycle, which is totally away form the day of ovulation so there isn't any remote possibility of fertilization. For the abdominal cramps which are actually occurring from 6 days after the placebo tablets were taken or you can say 27th day of cycle, so are are actually a sign of pre menses or beginning of your normal menstrual cycle. Also you should know that abdominal craps are never a sign of any sort of early pregnancy.
Now for your further knowledge and future protection make it very sure that you are not missing the hormonal
tablet beyond 12 hours otherwise you would be needing an extra protection.
So enjoy the day and relax.
Hope this information will help you.
Dr Sanjay K Kanodia
MD (Dermatology and STD