I am a mother of 18 months old baby..Post delivery my period cycle got so much disturbed..i get my period every month but it is very irregular..sometimes it comes a week after its due date ..sometimes 10 days ..sometimes more than 15 days too..i got my second dose of vaccination in oct month n my period was due on 7th of this month n still got no period..i am done with my pregnacy test too few days back n the result was negative..dont know why my period is so irregular.due to this i have severe backache also..kindly suggest me something..thanks .