(INSIDE EDITION) - While most families are enjoying their kids' first day back to school, this Ohio family is in mourning.
13-year-old Peyton West of Goshen collapsed on his way to classes Thursday.
He died later that morning.
"We don't know why," his dad Corey West told WKRC. "We don't understand it but we know God has a purpose and Peyton touched so many lives in just his short time here."
Peyton was born with hypoplastic left heart syndrome, a birth defect that affects blood flow to the organ. By the time he turned 5 years old, Peyton had already gone through three open-heart surgeries.
In March, Peyton was given a life-saving heart transplant as doctors said his heart was beginning to fail, and his family was relieved when he tested negative for any signs of rejection.
The family of 12-year-old Derek, who donated the heart, came to visit with the family in May.
However, his parents wrote on Peyton's Facebook page they were monitoring a couple of worrying signs that the boy continued to exhibit.
"As much as he smiles and jokes, he's been having some symptoms the last few weeks," they wrote in a Facebook post three weeks ago. "We have spent the last week getting tests and lab work done to try and figure out why he has had a cough for three weeks and why he is so tired all the time. Then today, he started with sweating quite a bit for no known reason and his stats bobbling up and down."
Through the pain, Peyton stayed positive and was always smiling and playing with his little brother Nolan.
Thursday morning, Peyton's family said he was excited to go back to school for the year. His parents had taken a photo of him getting ready to leave for school just 15 minutes before he collapsed.
"He went to bed, no problems. He woke up, no problems, being his goofy self," his dad said.
Students at the Goshen Middle School had a memorial for Peyton Thursday evening.
"Peyton was a wonderful young man a courageous young man who always had a big smile on his face," school district superintendent Darrell Edwards said in a statement. "Certainly his battle and his challenges are well-known to our community."
While doctors are still unsure what happened to Peyton's heart, an autopsy will be performed to determine the cause of death.
To donate to the West family, visit their GoFundMe page.