Sorry TMI!!!

I’m 4 days late on AF and I never had this happen before, I know it’s old blood but is this my period coming of implantation bleeding? I don’t think I need to buy pregnancy test??!! Help! My boobs have been extra sore & tender & feeling real heavy for a week now, headaches everyday thru out the day, using restroom more often, I felt nauseous & dizzy 8 days ago