An Indiana family’s ordeal is helping raise awareness after their 4-year-son developed a rare infection, initially thought to be flu. The bacterial infection had spread to various parts of his body, eventually leading to the amputation of his right leg.

Parents, Megan and Ben Crenshaw, thought their youngest son Bryson had caught the flu when he first developed a fever in early January.

Bryson was treated at home in the beginning, but when his fever did not subside and his heart rate became fast, his parents took him to the emergency room.

"He laid across my chest and it felt like his heart was about to explode," Ben told Good Morning America. "It was like, 'OK, let's go now.'"

The Crenshaws said even the doctors in the emergency room thought Bryson had the flu, but when they noticed he was limping a little in his right leg, the medical professionals at the local hospital had the boy transferred to Riley Hospital for Children in Indianapolis.

When Bryson reached the hospital, his right leg had become red and swollen, the Crenshaws said. Their son was diagnosed with necrotizing fasciitis, a rare bacterial infection, according to the Centers for Disease Control and Prevention (CDC).

Also called the "flesh-eating disease," the infection can spread quickly, and destroy tissues in the body. The condition can turn fatal if not caught early on.

Though necrotizing fasciitis is usually contracted via a cut in the skin or insect bite, Bryson did not have any of the sorts, according to his parents. In those cases, infection is mostly caused by a group of bacteria called group A streptococcus (group A strep), according to the CDC.

Group A strep also causes other common infections like strep throat and tonsillitis.

"We could not process it," Megan said, ABCNews reported. "When we initially got to Riley, there were just so many people rushing in, talking to us, wanting information, getting information."

"All we kept hearing from every doctor was, 'Your son is the sickest kid in the hospital right now,'" she continued. "We didn't even expect for him to make it through the first few days because of how sick he was."

Bryson spent a total of 55 days at the Riley Hospital for Children, where he was kept on a ventilator machine to help him breathe.

Bryson underwent surgery in which a part of each of his small intestine, colon, and the appendix was removed by the doctors. The infection has caused the tissues to become necrotic.

In one major surgery, amputation had to be performed on Bryson's right leg, where the infection had first appeared. Since the infection had occurred high in Bryson's leg, doctors were able to preserve and use some of his non-affected lower leg. This will allow the boy to walk on a prosthetic later, according to Dr. Christine Caltoum, medical director of surgical operations and division chief of pediatric orthopedic surgery at Riley Hospital.

"Part of his lower leg was actually used to extend the length of his amputation," said Caltoum, who was an integral part of Bryson's care team. "That allows for a longer part of the leg to be salvaged to make that a bit more functional leg for prosthetic use later on."