What Causes Delayed Periods With Lower Abdominal Pain?

Hello i m 23 years old , I normally get my period around 23rd-25th of every month , Last month I got my period on time after which I took Prostinor 2 due to unprotected sex. Again I got my period at the start of this month (July). During the month of July me and my fiance had sex twice and we used protection during the first time and not the second time . So I used Prostinor 2 again. I m late for my period and have been having lower abdominal pains. I m not tired or I don t have any other symptoms of pregnancy. Should I be worried ?