But Actifizz, the fracture was identified at the hospital straight away hours later. How do you know there was anything to be seen at the time? This is entirely your assumption, and there's nothing in the OP to suggest that was the case. In fact, the OP says they checked it at the time and deemed it to be fine. This is common in fractures and happens a lot.
I'm reminded of a time when my daughter had a gymnastics birthday party, and one little girl hurt her ankle. She cried, we pulled her to one side, she was assessed by the paediatric trained first aider at the time, and my dad who was also a first aider and she seemed fine. She walked at least 6 metres (across the length of a gym) with no complaints at all. She didn't hobble, flinch or anything she walked perfectly normally. After the initial pain, she didn't cry when it was touched, she went on to continue running around as if nothing had happened. We asked her if it hurt, and if she wanted us to call her mum. She said no she was fine. There was no bruising no marks, nothing! Later on that evening, I had a furious phone call from the mother who was angry that by the time the girl had got home, her ankle had swollen and black and blue. But what should I have done - the girl fell over and hurt herself, she then walked perfectly normally, didn't say anything hurt, had no obvious injury at all, and didn't want me to call mum. I told her mum at the end of the party and she left perfectly happy. I know I have the photos of her running on her foot quite happily after the event! Yet, By the time she got home it had blown up and the mother just would not believe me that there were no signs at the time. She was insistent that I must have seen something. Nope, not a thing. So should I have phoned her and called her in to say and "your daughter fell on her ankle, but there is no sign of any bruising, she can walk perfectly normally, does not seem to have any pain, is happy to run on her ankle and doesn't want me to call you". That just seems overkill! Yet she ended up in A&E hours later with her ankle.
Quite often injuries do not always present themselves much later and you cannot judge what is what like hours later to say what it was like at the time.