First of all, I would say your laziness is affecting your grades (unless it is otherwise). I’d reframe your mind to think about it as your period may affect your grades.
Secondly, I had horrible horrible periods and went on birth control. It’s not for everyone. But if you’re able to talk to a dr about it or go to planned parenthood for a consultation, it may be right for you. Do your research, trust your dr. And see if you’d like that. My birth control doesn’t make me gain weight or moody, or emotional, or anything like it does to some people, so it’s been an awesome thing for me. I much prefer it to missing school/work/activities (the thanksgiving I spent on the couch in pain) and I much prefer it to throwing up for two days.