OMG What am i going to do about this?

My 16 month old ALWAYS is hitting his head on everything, his legs kind of go inward, butat 11 mon when he started walking the doc said they would straighten out but they are still inward and he walls all the time and hite is head on everything, and today he was walking around a chair and fell and hit his head on i and has a huge knot on his head, i am so afraid he is going to do this on our fireplace or outside on the asphault,