wow so you had no intercourse,,did he finger you??
idk maybe you should go back for another blood preg test,,
i have never heard of anything like this
I wouldn't worry about your period not starting especially if you haven't had any sexual intercourse it would be IMPOSSIBLE to get pregnant. You are more likely having problems with ovulation and if you are then your period wouldn't start without medication to start it. Wait the week or so and if it doesn't start then see your doctor.
If your doctor told you to within 10 days your period will start, and you are at 4 days, then wait 6 or 7 more days.
If your period does not resume after that, see your doctor again.
As a side note, are you severely dieting, or engaging in excessive physical activities? Have you recently come off a Mirena IUD, or off Depo Provera injections?