Implantation or period??? HELP!

My period is now 4 days late, I've never had a Late period so this is unusual.. Two days ago I had cramps like my period was going to come but it didn't come. Now today I'm nauseous really bad mood swings and a few cramps with extremely sore boobs... Also today I went pee there was a few drops of blood nothing major just a few wasn't my period. Also took 2 test both came out negative .. Is it to early to know???? What does this mean???