Had period 2 weeks ago. brown spotting past 2 days and having another period. what could this be?

Hormonal fluctuation: There are a number of factors that can affect a women's hormonal cycle. Birth control pills certainly do, but other medicines, stress etc may affect it also. If this happens for more than 2 cycles, increases in amount of bleeding beyond normal periods or is associated with pelvic pain or other symptoms, you should be seen by your physician.