Hi and thanks for the query, the commonet cause of delayed periods in a woman of reproductive age is pregnancy. It si advisable always to do a good pregnacy test to exclude this. However, it is not unusual to experience missed periods in non pregnant women. Abdominal pain desrves a keen clinical evaluation. The location , intensity, aggravating and relieving factors, associated symptoms, past medical and surgical history are all important parameters in the evaluation. It would be interesting in your case to have acreful medical examination by a gastroenterologist. Blood tests like liver function tests, pancreate amulayse levels, fasting blood glucose, complete blod counts could be useful. An abdominal scan could also be very useful. I suggest you get an appointment with the gastroenteroligist for a proper clinical evaluation. Luchuo, MD.