Toddler fall

Tonight my 18mo was playing on the bed with his brother (a family member was with them). He stood up and fell backward off the bed onto the hardwood floor. He fell flat on his back. I watched it but it was like slow motion - I couldn’t get there fast enough before he fell. We immediately iced his head. He cried 5-10 min then snuggled with us. He ate a snack. Read a book. He was talking and walking. We kept him awake for 1.5 hr after. I have his owlet on him tonight. I’ve never experienced this hard of a fall with my first so I’m quite anxious and worried. Google is not helping. I’m so worried about a head injury. I did contact the pediatrician who said watch him closely for 24 hr. Any thoughts/advice for a worried mama?!