Suffering very bad period pains!!!!!! help!? ?

so basically I'm suffering cramps which are painful I'm taking tablets and they aren't helping much and u don't think I can go a day at college tomorrow. how can I persuade my mum to give me the day off? when she's already said no :( please help all I've been doing all day is eating chocolate and been cuddled upto a fleece blanket and hot water bottle