CD 17 but bleeding or spotting please help

I am on CD 17. I check my CM every morning in the shower. this morning it was EWCM with a tinge of red blood. that was about 7am. then I just went to the restroom at work and when I wiped it was dark red and was enough to cover the tissue. I put a pad on to protect myself and see what happens. I then went again and it's almost bright red and I have cramps.update now this evening it's darker and almost gone but still having cramps. has this happened to anyone before? I'm usually at a 28 to 30 days each cycle. according to Glow I should ovulate tomorrow on 3/20. But I'm so confused with the bleeding! HELP!