Helpint Period pains?

helloo :) i'm 15; i'm at school just now; and been to the toilet and my periods have started :( i'm normally off school because i'm thin and weak so my periods are always unbearable. I've been to the doctor before and they're offered to put me on the pill but i've decided to just cope with the pain with the help of strong painkillers. It's 3days till christmas and i really don't want my pains to disrupt christmas! How can i ease the pains?