Can plan b cause early period?

I took a plan b 2 days after my period ended. Exactly 1 week later I had a period again, lasted 4 days (my usual).

It has now been 3 weeks and I’ve been nauseous every single morning and night for the past 7 days. I’m wondering if the plan b induced period should counted as a “real” second period?

If I count it as a real normal period, then that puts me one week before my next period. If I don’t count it as a period, then that puts me 5 days late for my regular period.

Took the plan b on Nov 20th, same day as unprotected sex