Hello thank you for your query. Dysmenorrhoea or painful periods sometimes do occur . Also, one possibility is endometriosis that causes severe pain during menses. However, if this was an isolated event, you need not worry about it, as certain ovulatory cycles would be painful. If it is a pattern repeated every month, you need evaluation for it. Make sure you know your fertile days ( around ovulation ) and try accordingly. Take regular folic acid supplements. Maintain an ideal BMI take care.