I need help

I’m so sorry idk if this is the right sub to ask this but I just need urgent help. I’m in chem 2 right now and my midterm final exam score just came out as a 55. I’ve never liked or quite frankly understood chem. I ended with a B last semester, and was hoping for an A but that’s out the window. My question is how can I study better to atleast try to end with a B. Right now I just do practice problems and I get it fairly well, but during test time everything comes crashing down. Any advice would be very helpfully as I’m really stressing out.