Hi! Good evening, I am Dr Shareef answering your query. Unprotected sex could give rise to a pelvic infection which might give rise to pain in the lower abdomen. However, an unsuspected pregnancy can not be ruled out and so I would prefer a serum HCG to rule this out and an ultrasound abdomen to be done to know the state of pelvic organs. Therefore, I would advise you to get your self clinically assessed by a gynecologist, and go for the investigations as per her advice for further management. I hope this information would help you in discussing with your family physician/treating doctor in further management of your problem. Please do not hesitate to ask in case of any further doubts. Thanks for choosing health care magic to clear doubts on your health problems. Wishing you an early recovery. Dr Shareef.