One day after undergoing emergency surgery for what was initially thought to be a spinal infection, Abby Lee Miller has been preliminarily diagnosed with non-Hodgkin’s lymphoma – cancer that develops in the lymphatic system, PEOPLE confirms.

“It was not an infection, it was a type of a non-Hodgkin’s lymphoma – it’s a type of a cancer,” says Dr. Hooman M. Melamed, an orthopedic spine surgeon at Cedar Sinai Marina Del Rey Hospital who has been treating the star. “We’re getting an oncologist involved and we have to figure out what the next steps are as far as chemotherapy or radiation or more spine surgery. Depending on the tumor type, depending on the sensitivity of the tumor – it just depends the type but I feel more than yes, she will undergo chemotherapy or radiation.”

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The doctor adds that it is a “preliminary diagnosis pending pathology and oncology results.”

Miller went into the emergency room after she experienced “excruciating neck pain” and weakness in her arm and after her condition deteriorated over the next couple days, Dr. Melamed performed emergency surgery for a multi-level laminectomy at about 1 a.m. Tuesday.

Image zoom All Access/SAF/Splash News

“If we didn’t do something, she was going to die,” Dr. Melamed previously told PEOPLE. “Her blood pressure was bottoming out. She was not doing well.”

After the four-hour-long surgery, Miller began to feel more sensation while recovering in the ICU.

“She’s made some recovery in 24 hours, which is better than no recovery,” he said. “Nobody wants to end up thinking they’re going to be paralyzed for the rest of their life. That’s a reality that’s facing all of these patients going into it. All you can do is pray and, as a surgeon, you maximize everything you can for the spinal cord to recover itself. I am hopeful.”

While Dr. Melamed says he’s more “optimistic” as Miller is now starting to regain sensation, “we’re still not out of the woods.”

“There’s a chance this can spread to any part of the body … this is probably coming from somewhere else,” he says. “We don’t know where the source is. Any tumor that spreads anywhere is automatically Stage 4, but we have not determined the stage yet.”

RELATED VIDEO: Abby Lee Miller’s Surgeon Reveals Star ‘Was Going to Die’ After Developing Serious Spinal Infection

While Miller continues to recover in the ICU, Dr. Melamed says she seemed “encouraged.”

The star was hospitalized recently for a thyroid condition two weeks after she entered a halfway house. Miller was taken to an emergency room in Los Angeles, according to TMZ, which first reported the news.

Miller had been serving her 366-day sentence for bankruptcy fraud at the Victorville Federal Correctional Institution in California since July.

Image zoom Abby Lee Miller/Instagram

She was transferred at the end of March to the Residential Reentry Center in Long Beach, a facility that provides a structured and supervised environment where she’ll be given employment counseling, job placement and financial management assistance.

In May 2017, Miller received a sentence of one year and one day in federal prison, followed by two years of supervised release for bankruptcy fraud. She was additionally fined $40,000 and ordered to pay the $120,000 judgment, as well as give a DNA sample relating to her felony charge.

Earlier this year, Entertainment Tonight reported Miller had lost about 100 lbs. and was feeling “great.” And Miller posted a photo of herself on Instagram in January wearing a prison uniform and posed up with some of her visitors.

“Sometimes in life you make mistakes I trusted the wrong people and didn’t pay any attention to things I should of. I’m more than sorry for the mistakes I have made,” Miller wrote in the caption.