'I Am Shauna Rae' Sneak Peek: Shauna's Mom Worries Her Daughter's Brain Cancer Could Return

Shauna Rae's mom is opening up about her fear that her daughter's brain cancer may return.

Shauna, 22, was diagnosed with a rare form of brain cancer when she was just 6 months old. Treatment helped her into remission, but also left her pituitary gland almost dormant and stunted her growth. As a result, Shauna now stands at 3 feet and 10 inches tall, which is the average size of an 8-year-old.

In PEOPLE's exclusive sneak peek at the new episode of the TLC series documenting her story, I Am Shauna Rae, she tells her doctor she's been experiencing headaches recently.

"I have migraines, I wake up with them most of the time, I go to bed with them most of the time. It's something I've sort of grown used to," Shauna tells the doctor, who replies, "That doesn't sound great — they're happening almost every single day?"

"Yeah, I have one right now. Like just a slight throbbing. And position wise, when I lay down I get nauseous and sensitive to light," Shauna says.

The doctor then recommends Shauna go to the neurologist to make sure that the migraines aren't indicative of a larger problem.

"For the past few years, she's been developing pretty significant headaches, she's getting nausea, she's getting sensitivity to light and sound so some of those are classic migraine symptoms," the doctor says to the cameras.

She continues, "But you have to remember as well that she has a history of brain cancer so I did recommend that she go see the neurologist to go into more detail before we come to the conclusion that it is just classic migraine."

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In a confessional with her mom Patty, Shauna admits that her cancer returning is always a concern.

"I think the cancer coming back is definitely something we both worry about because we know how brain cancer is not something to joke around with, especially the form I had," she says.

"It's not a matter of if, it's a matter of when, so anything that happens to Shauna, we take it extremely serious," Patty adds.

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Patty then grows emotional as she recounts her daughter's cancer battle.

"After Shauna's surgery to remove the cancer, there was still more left — they couldn't get it all — so she had to do chemotherapy and you hope that it takes care of it all, you never know," she says. "But they did let me know that it would always be a concern, that it may come back."

"I really worry that it's going to be a reality," she continues. "It's almost more than a possibility, it seems like it's going to happen. It seems like I'm always waiting for the ball to drop."

I Am Shauna Rae airs Tuesdays (10 p.m. ET) on TLC.