Possible pregnancy

Had my period May 1-6th and I had spotting for 3 days this past week now it is gone and I am starting to feel sick, my body is really achy and I have been having a lot of headaches just feel sorta out of it I read about implantation bleeding and I am convinced that is what I had happen to me took a pregnancy test but it said negative which I think it is too soon to tell I plan on taking another in two weeks anybody have this happen to them and then become pregnant?