Brown spotting for 6 days.. what could it be??

Claire🌈🌸🌴 • Previous stillbirth 👣👼🏼 now Mother of 3💕

So my period should of started 8 days ago and I started spotting 6 days ago (brown spotting). And I’m still spotting now. I don’t need to wear a pad as it’s only when I wipe.

Iv had lower back pain for about 5 days, very tired too.

Iv done a few pregnancy tests. And they have all been negative.

I’m very confused on what’s going on 😣

Anyone experienced this and knew what it was?

Thanks