If you have a late period and a negative pregnancy test,then consider whether or not you've recently been sick,gained or lost a significant amount of weight,have been under excessive Stress or have taken any new medications. All of these things can affect your menstrual cycle and cause you to have irregular periods. Additionally,certain types of birth control,including the birth control pill,Depo-Provera and Norplant,can cause you to have Menstrual cycles disturbances.
Most of these problem are as a result of hormone disorders. She should see another doctor. If by any reason hormone like prolactin is trigered to go up either by family planing methods we use or it fails to come down after breast feeding,then it suppressess ovulation.
BOBB