I AM 31 YEARS OLD LADY HAVING 6 YEARS OLD

I AM 31 YEARS OLD LADY HAVING 6 YEARS OLD SON. I AM FEELING PAIN ON JUST ABOVE THE CEASORIAN CUT MARK FROM LAST 5 YEARS. MANY USG HAVE BEEN DONE. DURING LAST TEST DOCTOR DETECTED IT AS SCAR ENDOMETERIOSIS. THEY SUGGESTED FNAC TEST. THEY PRESCRIBED 21 DAYS CONTRACEPIVE PILLS AFTER MY NEXT MENSTURATION. BUT FOR MY NEXT MENST. IT IS 12 DAYS LEFT. I WANT TO DO FNAC TEST AS SOON AS POSSIBLE. SO PLEASE TELL ME THE PROCEDURE OF FNAC. CAN I DO IT EARLIER AS I M FEELING PAIN? ACCORDING TO THE ABOVE PROCEDURE IT IS MORE THAN ONE MONTH LEFT TO DO THE TEST.