Birth control

The past few months I’ve been having really bad periods. From horrible cramps to getting dizzy, hot flashes, almost passing out and getting close to throwing up. I’ve recently just brought up the topic of birth control to my mom and she seems to hate the idea of me being on birth control just because I’m not sexually active. She tells me to take vitamins and just take care of my health but I’ve been doing that and nothing has changed. What should I do? I turn 18 soon so I’m thinking of just getting birth control when I can on my own but right now she’s still denying the idea that I should get birth control.