Period/ pregnancy

I was one day late, today at 11:20am i went to the toilet wipes there was a little bit of blood so I sent to my doctor they did a pregnancy test but it said neg and it's now 4pm and it's still the same no cramps I was wondering could this possibly be implantation bleeding?? My doctor said they will do other test in 5 days should I just got get a test from the shop and see as the ones at the hospital didn't look any good