Light positive then got my period 🤦🏻‍♀️

So three days ago I took a test because af was three days late and I had no symptoms of it coming. Test ended up showing very light positive, so everyone told me to re test the next day in the morning. I did and it showed no double line this time and yesterday had really bad stomach pain(not cramp pain either it was worse) and spotting. During the night had really bad cramps heavier than normal period bleeding. Has this ever happened to anyone? Trying to figure out what happened?