Why is my period two weeks early?

You might have: Break through bleeding related to imbalance of estrogen or progesterone.

Many possibilities: A period which is starting 2 weeks early can be bleeding at the time of ovulation due to the hormonal swingswhich occur then (ovulation happens 2 weeks before your period) or it can be due to infections, medications including some contraceptive methods,or illnesses like thyroid disease,diabetes/insulin resistancePCOS,adrenal problems,or pituitary problems, stress, weight, diet, or exercise changes