a better ending
I think a better ending would be:
Instead of at school, Trevor and the bullies have the fight near Trevor's house. His mom gathers Trevor and jumps in her truck (which Jerry fixed) and rushes to the hospital. Because of the truck, she's able to get to the hospital quickly.
At the hospital, Trevor's life is saved by a brilliant female pediatric surgeon. The surgeon emerges from the operating room and tells Trevor's mom that it was a hard fight, but she refused to give up on Trevor. As the mom thanks her, the surgeon says her job is emotionally very difficult because many of her young patients die. The surgeon says she has been depressed lately, but it's good news like Trevor's survival that makes her remember why she is a doctor. The viewers then get a flashback and realize the doctor is the woman on the bridge who Jerry saved.
So although Trevor's acts were selfless, they came back to help him in the end. It would be a nice message about how good deeds can make a circle.