Implantation bleeding ??

I am 4 days late and have tested neg on a home preg test .. 4 days ago (the day I was supposed to start) I cramped and felt like I was going to start but never did no spotting and cramps went away after a few hours .. Today (4 days late) when I went to the bathroom there was a very light amount of rusty red blood when I wiped.. Could this be implantation bleeding ?? Not cramping but I am nauseous at some parts of the day, sore breasts, headaches, and big appetite.. Please help