What Is The Pain And Swelling In Abdominal With Delayed Periods?

Hi I am a 47 year old female. I have had a 6cm right ovarian cyst that was removed two years ago. I again am experiencing right sided sciatia pain and abdominal swelling and pain. Last menses was February 10 and have not had one since. Could I have a returning cyst and should I be evaluated? Please advise. Thanks, Catherine