We thought our 3-year-old had a virus — it’s Stage 4 cancer

Scott and Natalie Bolton noticed their 3-year-old daughter, Ava, was exhibiting odd symptoms over the holidays, describing her as “lethargic, pale and vomiting.”

They thought she simply had a virus, but soon she developed leg pain and bruises around her eyes.

The Scottish couple say they rushed their little one to the pediatrician, who immediately advised the worried parents to take their daughter to a local hospital.

Clinicians reportedly believed the illness to be nothing more than an unresolved virus due to low white blood cell count, but a closer look at a bone marrow sample and a subsequent CT scan revealed Stage 4 high risk neuroblastoma.

“To find out our little girl had cancer was just devastating. Our whole world collapsed,” Scott, 34, told local news outlet the Daily Record.

“Initially you are thinking it is okay, it is just a virus. It will go away itself,” he continued. “To then be told she has cancer is nothing we could have ever imagined.”

To them, the diagnosis was “rock bottom,” he added.

Neuroblastoma, the culprit behind a primary tumor on Ava’s back and secondary tumors on her shin, hip, pelvis and shoulder, is caused by an overgrowth of immature nerve tissue due to genetic mutation.

For children in a high-risk group, the 5-year survival rate is about 50%.

The toddler endured grueling chemotherapy treatments at the Royal Hospital for Children in Glasgow, suffering side effects and undergoing a myriad of tests and scans that involved poking and prodding.

“She has amazed us all with her resilience, keeping her cheeky smile and making us so proud of how she is coping thoughout it all,” the family wrote on a GoFundMe page, which has raised about $172,000 as of Saturday.

Their goal is over $320,000.

Ava has completed six rounds of chemotherapy as of last week, according to the fundraising post, and the next phase of her 18-month treatment is a higher dose of chemo and a stem cell transplant.

“This phase will be extremely difficult for Ava and also us a family as its going to make her very unwell and leave her with no immune system meaning any infections or virus’s can become life threatening to her,” her family wrote online, adding that Ava will be kept in an isolation room for as long as six weeks.

Despite improving scans, Scott and Natalie, 34, fear their daughter could relapse — and the cancer could return.

The money is being raised to send Ava to Memorial Sloan Kettering Cancer Center in NYC, where a vaccine is being trialed to stop neuroblastoma from returning in cancer patients.

“Without this treatment, Ava is more likely to relapse reducing her chances of survival — this is something we are not willing to take a chance on,” Natalie told Jam Press.

The couple also have a 5-year-old son, Lucas. The family planned to host a fundraiser Saturday night.