IB or period?

Hi there just want to understand what is going on with my period (?).  A week before my period was due I had a little bit of brown discharge only when I whipped it lasted for about 2 days, now my period is supposed to start in 2 days but yesterday I stared having dark brown discharge so I had to put my pad on thinking it was my period. Usually my period comes with a little bit of cramps and it is not brown, so I am worried since it is not usual situation for me. Is there something wrong with me or is it something else?