MIAMI -

The baby whose life was saved along the side of the Dolphin Expressway is doing better, his mother said Monday morning.

Photos of rescuers performing CPR on five-month-old Sebastian de la Cruz have gone viral since the Thursday afternoon scare. His aunt, Pamela Rauseo, is credited with saving his life.

Rauseo and her sister, Paola Vargas, spoke with Robin Roberts in an exclusive interview with ABC News Monday. Vargas is a nurse at Jackson Memorial Hospital, where her son is currently being treated.

Doctors still don't know why Sebastian stopped breathing, but tests are scheduled for Monday to try to find out what happened. The infant was born premature and has suffered from respiratory problems in the past.

"Hopefully today we'll have some answers."

Vargas also had some exciting news Monday, announcing she is pregnant once again.

"Sebastian will be a big brother three days before his first birthday," she said. Vargas is three months pregnant.

RECOUNTING THE RESCUE

"We were in the car and I was driving and when he stopped crying I just really had a really strong feeling that something was off," Rauseo recalled. He appeared to be sleeping but when Rauseo touched him she realized his body had gone limp. "I was so nervous, my fingers couldn't dial 911."

That's when Rauseo got out of the car and began begging for help from passersby, driving along SR 836.

"It was very scary. I get very emotional just thinking about it," Vargas said, her eyes filling with tears. "He was purple, you know ... and me knowing what that means, it's very hard on me."

Compelling photos of the dramatic rescue have gone viral. One of the first people to rush to Rauseo's side was Miami Herald photographer Al Diaz.

Diaz ran through traffic to find help, returning to his car to get his camera when he felt Rauseo had the help she needed.

"Once I got to see those images, it should me how terrifying it really seemed," Rauseo said.  "It's one thing to tell someone, its another thing to actually see it."

Members of their family are planning to renew their certification for CPR and have said they have heard from many supporters who are planning to do the same.