Stalker

Ok I’m in 10th grade and this has been happening since school started 3 weeks ago this one girl in the locker room let’s call her Kim. So Kim changes really fast so she can wait by the door. a perfect view from my gym locker, so every day I see her walking back and forth in by the door watching me change I’ve caught her multiple times and even had a couple friends watch her looking directly at my butt. Idk what to do please help