implantation bleed or clomid?!? help me

okay guys, I took 50mg of clomid on cycle day 3-7. I am currently on cycle day 26 and I have extremely brown spotting, not even enough to cover a tampon. my period is due in 4 days and I've never had a day where I spot. it's usually just full on period. why is this happening? is it the clomid or could it be implantation bleeding?