My period is late, i'm having headaches sometimes and also feeling tired?

Some thoughts...: In a woman with regular periods, some causes of a late period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, medicines (like birth control pills), hormonal imbalances, etc… Seeing one's doctor is a good idea if symptoms are persistent, recurring, or worrisome. Pregnancy is the common cause of a missed period if sexually active.