Thank you for your question.
From time to time during the course of a woman's life, there is a high probability that she will be experience irregularities during her menstrual cycle.
However there are some other factors that can bring it on as well. Stress is a big one. So if you're admitting to an enormous amount of stress, it's very likely the culprit. Medications can cause irregularities and so can increased exercise
I hope this helps.