I know just exactly how you felt. When my deceased Yorkie, Delsi was only 4 months old and weighed only a little over one pound, I picked her up and put her up to my shoulder to take her outside and she just gave a push off over the back of my shoulder and landed head first on the metal door jam, and that was a four foot drop. She was knocked out and we rushed her to the Vet. but she woke up on the way. They found nothing wrong with her on the x-rays.
These little ones sure can stand a lot of pounding sometimes.
I'm so happy your baby is fine. He knows it wasn't your fault, and it sounds like he's still trying to cheer his mommy up.