If you haven't had your period and think your pregnant then lift on something heavy and start your period, what can that mean?
I think it just so happens that you were getting your period already however, if you see or feel a difference from this period compared to the others get to a Dr.
most likely miscarriage if you are pregnant
Possibly a miscarriage, you would have to go to the doctor and get you blood levels checked.
By not knowing you were pregnant, it may just be a coincidence and you just got your period.