9 month olds head 99th percentile? 😐

So my daughter since birth has had a head that’s 95th percentile but the last 2 visits it has went up to 99th. Doctor wants to run tests. I’m freaking out even though her dad has a huge head and as a baby has to have tests and he was fine. The thing I don’t get is her head doesn’t even look big? I’ve never gotten a comment on her head and it doesn’t look abnormal to her body to me. Just wondering what you guys think?