Im so confused... I usually start my period around th 28th and I skipped my period in July but instead......?

I started my period on the fourth of august and it last about seven days. I had on the sixteenth.Then i noticed on the twentieth i started discharging brown blood but it only showed up when i wiped and was only worth maybe one liner a day. However, this brown spotting has been lasting for six days now. So could i be implantation bleeding??? Someone please give me some answers if you know implantation bleeding can last for six or more days!!!