I'm just now seeing this. I was acutally laughing the entire time because I "knew" from the title what it most likely was. I was wrong, though. I thought it was a rock/pebble.
The old acorn cap trick - yup, I know it well. When Mandie limps now, I always first check between her pads and toes before freaking out (and so far..it has always been a pebble or an acorn cap making her limp).
Bless your heart. You sure have a way of telling a story!!