Hi ! Good evening. I am Dr Shareef answering your query.
The symptoms you have described could be due to a mild form of 
appendicitis, or a chronic ectopic (using birth control pills are never a 100 % guarantee against a 
pregnancy. If I were your doctor, I would advise you for a personal clinical examination, followed by some blood tests like 
complete blood count, a serum 
HCG, a urine test (both routine and culture sensitivity), followed possibly by an 
ultrasound of abdomen to rule out any pelvic disease/pregnancy/ureteric calculi. A gyneacological examination might also be advised if need be. Further treatment would depend on the results of the clinical examination and relevant investigations. However, I would advise you to visit the emergency room of your nearest hospital to avoid any further delay in treatment.
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.