Miscarriage and Contraction cramps

So me and my fiancé was TTC this month (been trying for 10 years) we bd all month long. Then I miss my period 2 days but cramping in my right side, lower back and lower belly 13-14dpo (negative test). So I’m like ok this my period. All of a sudden my period stops (what I though was my period) gone then I want to say 11 hours later contract pains every 2-5 minutes. I remember the pains oh so well from my other pregnancy. So I hope in a hot tube of water and lay there and the pain still was coming and going every 2-5 minutes. All of a sudden I feel pressure and a small blood cloth comes out. But right before that I took 3 8 hour pain reliever pills cause I don’t like pain. Now I’m just bleeding thick reddish brown blood. I took a test this this evening when I stopped bleeding and it was positive which is crazy because I though I was on my period. Can anybody explain why???? Any information will help me understand. I’m gonna schedule an appointment for next week but this crazy..