Opk positive for 3 days

Michelle🐶 • 8 angel babies, now divorced but still hopeful for my first human child - already have my pitbull fur baby!!
Did I do something wrong? I tested Sunday and it looked positive, Monday was positive as well and I figured it was the surge going down (Sunday up Monday down) I just tested again and I have an even darker line? I don't get it. I was cramping badly yesterday so I assumed it was ovulation. Should I be positive 3 days?