Hi,
Welcome to the forum nd thanks for posting on it. 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.
Other important and frequent causes of irregular periods are PCOS and fibroid uterus. 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 pls consult a gynecologist.
I hope i helps. Tak care and regards.