Implantation bleeding or miscarriage ??

I’m 4 weeks pregnant. Starting bleeding yesterday around noon and it continued on and off just little here and there started brown to dark red just light bleeding, stopped around 6 then this morning once I got to work it was a browning dark red and its medium flow but I’m worried it’s still too much for implantation bleeding..... I also had light period like cramps yesterday on and off and lower back aches nothing too bad tho. I was tested two days ago HCG blood test and was confirmed 4 weeks and okay.