Ovulation test embarrassed

I read that an ovulation test always has 2 lines because of hormones in our body. However the ones I get from Amazon have definetely been blank when I'm not anywhere near ovulation. 
I'm actually on cd 20 in a 28 day cycle and got a faint second line that shocked me. I've never tested this way unless I'm testing before ovulation. I also had a bit of dark blood this morning. I've only had one cycle since the birth of my baby and wood like opinions. Thanks