What's happening

Totally baffled, I was due AF on tuesday and have had all the pains but no AF. Had a false test but going to do another tomorrow (first wee). But all day everyday since Monday I've had the most horrendous period type pains. It feels like my womb is swolen and really bad back pains. I can't sit down without shooting pains in my womb n back. Starting to worry now as no AF n no positive test 🤔