Mom Visited with Her 4-Year-Old Son and Dad in Hospital After Welcoming 2nd Baby. Hours Later, She Collapsed (Exclusive)

A father is remembering his last moments with his “amazing” daughter, who had a medical emergency after she underwent an emergency cesarean section last month and later died.

“She was just a great mom,” says Jason Simpson of 33-year-old Cassidy Arnold, who was able to spend time with her newborn son before her condition took a fatal turn before Thanksgiving. “She was always just so happy and tried to make the best of everything.”

A child care manager at a resort near Lake Tahoe in California, Arnold shared a 4-year-old son, Charlie, with her husband, Trent Arnold.

The couple had looked forward to welcoming their second baby and already picked out a name. Leading up to her due date, on Monday, Nov. 24, Cassidy went into the hospital for high blood pressure and was given medication, including blood thinners.

Her doctors decided to perform a C-section and baby Sam was born that night. 

The next day Charlie was excited to see his brother, so Simpson took the boy to the hospital. 

“I got to hang out with her,” says Simpson, who remembers talking to Cassidy about what she wanted for dinner when she got home.

“It was just so normal. The baby was eating and she looked good,” he says.

Charlie even asked if he could see his mom’s surgery scar, which Cassidy said she’d show him when she was home. She didn’t expect to wait long to be discharged: Simpson recalls hearing Cassidy’s care team confirm that she’d be released the next day.

However, 30 hours after welcoming her son, Cassidy collapsed while in the bathroom. 

“I guess the nurse heard her make a noise,” says Simpson, who adds that Cassidy’s husband was at the hospital with her that night. “She never totally came back after that.”

The medical staff brought Cassidy back to consciousness for a short time.

“She was scared,” her dad says. “And then she went into cardiac arrest.”

Cassidy was transported to a hospital in Reno, Nev., where she died on Wednesday, Nov. 26.

Her family, who is still reeling, is not sure what happened though they’ve been told her cause of death was postpartum hemorrhage. An autopsy is being conducted.

“What happened? We just need to know what happened,” Simpson says.

He has been staying with Trent to help care for Charlie and newborn Sam, who is thriving. Originally, Trent and Cassidy had selected a different name for their child but Cassidy loved the name “Sam.”

After her death, Trent decided to switch to her preferred name for their baby.

“He’s pretty easygoing,” says the proud grandpa of the newborn, “He’s a little bit like his dad. He likes to be up at night, but he’s been a pretty smooth little boy.”

Simpson and his son-in-law are trying to maintain normalcy for Charlie, who will turn 5 later this month. When he went back to school, Charlie asked his grandfather to share a picture of his baby brother with his class. 

“I thought [that] was pretty cute,” Simpson recalls.

As the family finds a way forward, they’ve been lifted up by their community and the people who knew Cassidy from Heavenly Ski Resort, including the children who loved her so much. 

“That’s been nice to just hear people talking stories about Cass,” says Simpson.

Trent’s sister, Aimie Pieper, organized a GoFundMe to support the young family. It’s garnered more than $96,000. 

“Cassidy was one of the kindest people I have had the honor of knowing,” Pieper tells PEOPLE. “She was caring, loving, a wonderful wife and even better mother. She had a true passion for early childhood education and she will forever be remembered.”

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Simpson made similar remarks about his daughter, who, he says, only wanted the best for her two boys.

“She loved to see him [Charlie] experiencing life,” Simpson says. “He was always in the dirt and paint and living his best life.

He adds, “That’s what she wanted for her kids was for them to be happy and have experiences.”