Implantation bleeding???

I'm sure this question has been asked 1000 times but Google isn't giving me much help! According to Glow I'm nearing the end of my fertile window. Me and my OH have been trying really hard to conceive. Today I've had some brown discharge. I've heard some women get spotting when they ovulate but I've never ever had that in my 12 years of getting periods. What do you think are the chances it could be implantation bleeding?