Abnormal menstruation is a sign of hormonal imbalance or possible miscarriage. You can solve this mystery only by performing a pregnancy test. If you are pregnant, the vaginal bleeding was probably a sign of miscarriage. If you are not pregnant, vaginal bleeding is most likely your period (untypical, but still a period). I could give you more precise information if you gave me the date of your last NORMAL menstruation (before this bleeding). Further, you can consult a gynecologist to discuss the latest irregular period and your menstrual history.