implantation bleeding??

got a positive opk test about 10 days ago. I'm on a 34 day cycle. BD"d pretty much every day that week. today I noticed some dark brown discharge/spotting. alittle more than a few drops but not a full blown period. any thoughts what this may be? not due for period u til April 26th. I should also not I had implantation bleeding with my first child but can't for the life of me remember exactly what it looked like