Suggest Remedy For Delay In Periods

Hi, I am 16 years old and have not had my period this month ...I was due about 7 days a go and still nothing. I am a virgin so NO I am not pregnant. The only thing I have changed recently is I have started taking biotin 1000mg a day. The last two days I have been getting cramps in my back but still no period...any ideas on what may be wrong... thank you