The horse tripped over a big rock. But I was ok. Too bad you caught it from your brother. I especially liked the way you used description, so I could feel like I was there. I also liked that you told a good horse story.
Most writers write a first draft, a basic story.
Then they go back and add more details, new scenes and more information. When you do that your story becomes even better, more exciting, and more full. Before you write your second draft, I wanted to tell you about a few picky things that will make your story stronger. For a second, I thought the nurse was hurrying to the hospital. I know that can sometimes be confusing when you are writing.