Wtf do i do! Worst period pain ever

Before you read this just note that i've never had period pain ever before not even a tiny cramp.... 
I've just had the worst period pain, nearly called an ambulance, i woke up and just puked and then had cramps and then i got like some kind of shakes and sweats and then i blacked out and couldn't see anything, then i tried standing up and couldn't so i had to literally lie on the bathroom floor and i fell asleep or i fainted not really sure! This went on for 2 hours  
What should i do next time this happens? And why is this happening to me x