help!!!!!!!

ok so my period ended about a week ago and everything's been fine until 1-2 days ago when there was blood mixed in with my discharge!! i didn't think much of it but it's not stopping. there's not a lot it's just mixed in with it, but should i be worried? i'm 14 and i'm not sexually active obviously and i haven't taken anything or whatever... what's going on?? has this happened to anybody else?? should i be worried it's something bigger like cancer or what..!!??