Possibly pregnant??

I was supposed to get my period yesterday and it was supposed to last 4 days  , but two days before I had pinkish/ red spotting and it stopped last night but I'm still supposed to be having my period , my nipples have been really sensitive lately and I keep feeling like I'm gonna throw up , could I have been experiencing implantation bleeding and my nausea and sore nipples be a symptom of pregnancy ?