There is no real way to know until you undergo a physical exam by a doctor. There a number of reasons for bleeding, other than a menstrual period. Some of these are listed in an article Merely Me, a writer for this site, wrote, called, Bleeding In Between Periods: What does it mean? It doesn't fit your exact question but does list some causes. If it's an ongoing condition, and it is not normal, it should be investigated by your physician.
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