please help me ,, TMI WARNING

i’ve been on the pill for over a year and out of all this time i’ve never experienced anything like this .. my period is a week away and i’m getting brown spotting in my underwear ? at first i tried not to panic but it’s been going on for four days now .. usually the worst of it being sometime in the morning ,,

i’m wondering if me exercising has caused it ? i just recently started doing ab / thigh exercises and could doing those so frequently have caused this ? or did my period come early somehow ??

i’m so scared what is this