Hun, If I had a dollar for every time one of mine have fallen off things and onto their heads, I would be rich. Seriously, he does sound like he is fine to me, but do keep your eye out for possible concussion etc JIC cause it might not be a problem now, but sometimes it can be later kwim?

It's not your fault at all, these things do happen sometimes and it's always so quick that you never have a chance to stop it He'll be fine and so will you.