Hello,
There are numerous reasons for having irregular periods. . High level of stress, cholesterol, hormonal imbalance, chain smoking, dramatic changes in your life style may be some of the common causes of you irregular periods.
If this was the first episode of irregularity in the periods, then wait for the coming cycle and try lifestyle modification by reducing stress and decreasing cholesterol levels. But if the repeat happens, then consult a gynecologist and get yourself thoroughly examined to diagnose the cause of irregular periods and start with the treatment. Moreover if it is heavy bleeding then get miscarriage ruled out.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
Hormone fluctuation. I've missed some before. If it happens every month though, visit a doctor.