I've had my period for 2 weeks this has never happen to me what can be the reason?

Hormones: Periods are controlled by hormones. Many women have problems. All you can do now unless you have symptoms is to watch and see what happens next. Keep accurate time records and review your past month of activities. Hopefully this bleeding is just a fluke but if you are symptomatic report immediately to your pcp. Stress, physical activity, etc may cause hormonal imbalance! . .L.