15 month old hit head 🤦🏻‍♀️

I know it happens... but I HATE it. He’s 15 months and walking/running everywhere. His favorite thing to do when we are in the kitchen is get the mop and broom out and “clean” the floor. I was wiping down the counter and he tripped beside the fridge while holding the broom and hit the back of his head on the fridge 😭 a knot immediately formed like the size of a grape. I tried applying ice but of course he continued to push it off. He’s had a knot on his forehead before but never the back of his head. Does this area call for more concern? He’s fine now, walking and playing and eating snacks. Just can’t help but worry