My Bella did the same thing with my daughter when she was a pup. My daughter is as tall as me. She got excited and squirmed and fell. She layed there stunned and acted like she got the wind knocked out of her. We took her to the vet , and she was fine.
They are little wiggle worms and I'm surprised it doesn't happen more often.
I hope Bella is OK. Keep and eye on her and give her lots of lovin'
