Meagan and Michael Xydias thought their 2-year-old daughter Kenni was simply constipated or experiencing a growth spurt when her stomach started protruding earlier this month.

The Senoia, Georgia, couple never suspected anything serious was wrong; Kenni’s pediatrician said she had gas and would be fine within a day.

“We sent her back to school and the daycare called me and said, ‘Her fever’s at 103 and we’re really concerned about her belly. It seems even bigger,’ ” Meagan tells PEOPLE. She became worried and took Kenni back to the pediatrician. “They said it was gas but I kept saying, ‘Something’s wrong. It’s not gas. Something’s not right.’ “

When Kenni went to Children’s Healthcare of Atlanta’s Scottish Rite hospital for an ultrasound, doctors found a mass growing on Kenni’s ovaries and diagnosed the toddler with a stage 3 ovarian yolk sac tumor on Feb. 15.

“We were heartbroken. My husband was confused as to how a 2-year-old could have ovarian cancer, like, how could this happen?” Meagan says. “I was just taken aback by the fact that my baby had cancer. Cancer, that’s what shocked me. I don’t think I heard much past that.”

The condition is a rare, malignant tumor of cells found in the embryo, according to the Cincinnati Children’s Hospital Medical Center. Its cause is unknown but symptoms include painless, firm swelling.

Shortly after the diagnosis, Kenni underwent surgery to have the large mass removed. Meagan says the surgery was successful and Kenni’s health began to improve immediately. She has been hospitalized since the diagnosis but is expected to be released in the coming days.

“It hasn’t felt like just two weeks, it feels like we’ve been here for a couple of months,” Meagan tells PEOPLE. “As soon as they took out the tumor, her color was better. She was breathing easier. It took her a few days to get back to her normal self and be playful. We’re happy to be able to go home.”

Meagan says Kenni’s health has seemed to be improving with treatment, but the family knows that even the slightest fever could land the toddler back in the hospital. Kenni’s chances of surviving the cancer are high and Meagan says she tries not to think about the possibility of losing her daughter.

“For the next few years she’ll be in and out of doctor’s offices. But hopefully that’ll be it,” Meagan says, adding that Kenni has remained strong throughout the ordeal. “She is full of spunk and sass, she’s sweet and she’s funny. She has a great sense of humor, she likes to rough and tumble with her brothers. She’s a handful, but a delightful handful.”