Can you tell me about secondary amenorrhea?

Periods stop.: Secondary amenorrhea is when a woman's menstrual periods stop unexpectedly at some point in her life after she had had normal menarche (beginning of menstrual periods) and had menstruated monthly for some time. It is usually due to something (ie. prolactin) interfering with the hypothalamus-pituitary gland's ability to produce gonadotropins (LH and FSH) needed to promote normal ovarian function

Multiple: Hi. The term "secondary amenorrhea" generally excludes the trivial causes of pregnancy and menopause. Ergo, assuming it's unexplained, there are genetic causes for premature ovarian failure (e.g., Fragile X Syndrome), gonadal toxicity (e.g., chemotherapy), and hormonal (usually androgens of adrenal or ovarian source). At age 47 (your stated age), I would have to say menopause is most likely.