I'm so scared

idk what the hell is going on with me but my period was roughly 2 weeks ago and it was a heavy full on actual period so not anything out of the ordinary at all. Ever since that period until now I've had sore boobs which doesn't happen & last night I got some dark brown discharge like I was about to start.. I was like okay what's happening so I wake up this morning and go pee and I've started my period two weeks early... My boyfriend and I haven't had sex in over a month & im not on the pill... This period is heavy like my regular ones but I'm not experiencing cramps quite yet.. What in the hell is going on? I have a regular period ever since I started so.. and I'm 17 if that helps anything lol