I trimmed the tip off the top part so she hopefully won’t catch it on anything. I thought about gluing it but I’m guessing it’s swollen. I didn’t want to seal anything in either. It’s the top that is sorta loose but not enough that it came off.
Not sure there is much I can do but keep it clean.
I went back and looked really closely at that nail.

The nails aren't overgrown or dried out looking or fragile looking.
She had to have caught it just right on the edge of something hard while running.

I would be trying to keep it clean too...I have zero advice I guess. Just still surprised she did that to her nail.