I am not sexually active, but i haven't had my period for five months. i feel normal though. i've had my period for three yrs now. what could be wrong?

See your doctor: There are a number of causes for secondary amenorrhea, or the lack of a period for at least 6 months after the start of menstruation. These causes include obesity, polycystic ovarian syndrome, being underweight, excessive exercise, or even increased stress. Despite feeling normal, you should see your primary care physician for help determining which situation applies to you.

Not ovulating: Most common reason is lack of ovulation, or egg release. This may be from something called pcos or if you are a thin atheletic individual, lack of ovulation would be from a different cause. With lack of ovulation, you either have low hormones or a lack of balance in the hormones. I would recommend an evaluation to prevent future problems as well as assess future fertility.

No periods: If you're not on any kind of birth control, you are probably experiencing secondary amenorrhea, for which the most common cause is chronic stress or tension which interferes with and suppresses some of the hormones necessary for a normal cycle.

Depends: It depends upon your age and other factors. For example are you on a diet or with recent weight loss? Are you stressed due to work or family issues. Also have there been any changes in your diet, level of exercise? A change in menstrual pattern can also be a sign of perimenopause. Best to check in with your primary care provider to make sure all is well. Best!