Advice?

I’m a senior in high school, and thought I’ve worked hard all these years, and I know I should be excited, it all feels short lived? All the classes are hitting me hard, and nothing seems to want to work out academically for me anymore. So I’ve just been kinda living in moments for fear if I think about the long run it’s all just gonna come crashing down on me. I’m kinda unsure what to do at this point.