A British teenager thought she was just feeling pain from a wisdom tooth, but it was actually a signal of a bigger issue— a rare and aggressive form of pediatric cancer.

Nadia Hobbs, 18, was massaging her jaw to relieve the pain when she found a pea-sized lump on her jawline, The Sun reported. By the time blood tests ruled out mumps and glandular fever, the lump had doubled in size and she was in “excruciating” pain.

Her mother, Rachel Hobbs, 44, was insistent she undergo further testing and took her to the hospital, where she was diagnosed with rhabdomyosarcoma, a childhood cancer whereby cancer cells form in muscle tissue. An MRI scan revealed a cancerous tumor in her cheek.

"The size of the tumor completely shocked us all,” Nadia, a student at Exeter College in England, told The Sun. “I couldn't believe how huge it was.”

Nadia underwent seven cycles of chemotherapy and has two more to go. The size of her tumor has decreased by 75 percent. The teen hopes the six weeks of radiotherapy she recently started will completely eliminate the tumor.

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Nadia credits her mother’s encouragement to go to the hospital with her early diagnosis.

"I haven't saved Nad's life by any means,” Rachel told The Sun. “I just kept pushing for a diagnosis and made sure she was treated as soon as possible, and now we are hoping for the best."

The teen is fundraising for Teenage Cancer Trust.