My nine week old kitten....?

ok so ive asked quite a few questions about him so sorry if you have read and answered one of my q's before and im boring u! anways ive had both cats and dogs in the past but recently got a kitten.... he is very playful which is fab and i love to watch him, but he falls off things and i worry he hurts himself as he is so tiny.. just earlier he came running into the kitchen and crashed his head into my leg... it mustve hurt him! he seems fine so maybe im just being a worrier?? as i cant always be at home...