HELP! AF not due til 11/29! Why am I spotting?

P.

AF isn't due til 11/29 but I started spotting 11/22 light pink. Took a pregnancy test 11/23 and got a bfn. Still spotting (light brownish in color).. Haven't filled up a pad just light spotting. Has this happened to anyone else before? Could this be my period a week early (Honestly it's too light in my opinion to be my period but seems too long to be implantation bleeding)? Help!