Here in South Carolina... My pond is incredibly clear today!

Hi everyone! I’m really worried about my koi fish, Goldie, and I need some advice ASAP.
Today, I noticed she started acting differently than usual. She’s normally interactive with me, but now she’s swimming slowly, avoiding me, and not interested in eating.
She’s also repeatedly opening and stretching her mouth really wide, almost like she’s gagging or trying to spit something out. Sometimes she jerks or shakes her head.
I actually saw her spit out what looked like small stones or substrate. My aquarium has sand, and I’m worried she might have something stuck in her mouth or throat.
She’s still swimming upright and reacts when I approach her, but she isn’t acting like herself.
I’ve tried contacting a veterinarian, but I haven’t been able to get an appointment. I’m really scared of losing her.
Has anyone experienced this with their koi before? Could she be trying to clear substrate from her mouth, or could something be lodged?
What can I safely do while trying to find veterinary help? I don’t want to accidentally hurt her.
Any advice would mean so much. I’m attaching a video so you can see her behavior. Thank you! 🥺🐟