Implant Bleeding/Miscarriage/???

Hi, I'll be 34 in October and have an almost 22 month old. My husband and I had sex on July 22. My period is expected Aug 5 (Saturday) and I'm very very regular!

Today (Aug 3), I started experiencing bleeding and cramping so out of curiosity, I took a pregnancy test. It came back and said Not Pregnant. I just don't know what I'm experiencing because my cramps don't usually feel like this and I'm so so regular. I'm just curious if it could be implant cramping/bleeding or a sign of miscarriage.

Any input is greatly appreciated.