I definitely know how this feels!!! It's the WORST feeling in the world! And that crying that they do is like nothing I've never heard. When we first got Ferdinand, a friend of my boyfriend's friend was over and holding him. She went to put him down but didn't have a good hold on him at all (pissed me off... I mean, he's a puppy, hold him tighter!!). Anyway, sure enough he jumped and landed on his head on our tile floor. He was screaming and ran away. I chased after him and just held him. I felt so helpless. As far as I know he's fine now... but maybe someone else may be able to shed some light on what might happen if they're dropped like that.
Anyway, needless to say I don't let many people hold him anymore. I felt so bad for him when it happened!