Hormone-producing cysts can cause irregular periods. Also talk with your doctor about any medications you're taking. Certain antidepressant drugs and anti-anxiety medications, for example, can affect menstruation....Lifestyle and environmental factors can have an impact on your periods, too. In some cases, high levels of stress may disrupt your menstrual cycle. Excessive exercise could cause periods to stop for a while. Extreme weight loss and eating disorders can affect your cycles, as well...Consult nearest gynecologists they will do the needful.