Has this happened to anyone before?

I have now taken 11 tests. All positive. Faint positives but definitely a line on all of them. Three days ago I started getting brown discharge (thinking implantation bleeding) this would be my fourth baby so I know how I feel when I'm pregnant. Today I started cramping really bad and bleeding like my period maybe a little more and passing larger clots than normal.

I'm convinced now if I was pregnant I'm no longer pregnant. The test I took this morning was way darker than the other 10. I'm just so confused.