Hi, It's Been Nearly 50 Days I Haven't Got My

Hi,
it's been nearly 50 days i haven't got my periods yet, usually i get once in 35 - 40 days.
What all the possible reasons for this delay, i am single no chance of pregnancy
Had my thyroid and pcod check in recent times and it's normal
Taking Norlut will delay the periods? as i have taken it per my friend's suggestion.
Please advice this stress is so unbearable