Where does this come from?

Hi. I really love jumping on my trampoline. But yesterday something happened to me on a friend's trampoline. I wanted to hop onto my knees and then do a somersault, which I've done a hundred times. But unfortunately, when I did the somersault, my full weight hit my head. My neck hurt a bit, but I carried on jumping and just did normal somersaults. But today, when I got on the trampoline and wanted to do a somersault, I somehow couldn't do it anymore. I jumped off with a lot of bounce, but then I kept falling on my stomach. I didn't mean to do it, but it was as if I couldn't move anymore. I panicked a bit and almost started crying. Do you know what that is? I'm terrified that I'll have to learn everything again and that practicing will be even more scared than before.