Last night's episode of Teen Mom 2 took a horrifying turn when Leah Messer received a phone call from her ex-husband, Corey Simms, who said that he was rushing their daughter Ali to the hospital. The seven-year-old — who suffers from a rare form of muscular dystrophy — was having difficulty breathing.

"Ali’s having a hard time catching her breath, and I think we need to take her to the emergency room," Corey said. "She said that she couldn’t breathe. Better safe than sorry." A producer proceeded to ask Leah if difficulty breathing is a symptom of MS, but she refused to answer the question. According to the Mayo Clinic, however, it is. Their website states, "Progressive weakness can affect the muscles associated with breathing. People with muscular dystrophy may eventually need to use a breathing assistance device (ventilator), initially at night but possibly also in the day."

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Leah told her daughter that she and Corey received an email from her teacher who said that she's been falling more at school. "She fell out of her seat and she fell a couple of times," Leah explained. "She’s having a hard time. She’s getting tired, saying her legs are hurting and tingling." Ali added that she doesn't have time to finish her lunch, which is when the 25-year-old suggested she get an aid to help her — and Corey agreed.

Yet this setback doesn't mean Ali is feeling sorry for herself. Just before last night's episode aired, the mother-of-three took to Instagram to post a positive message on her little girl's condition. She wrote, "Muscular Dystrophy won't stop our girl! We always want her to know that if she can dream it, then she can do it! We believe in her like she believes in herself! We didn't want her to feel different in a special needs class, but if it was in the best interest of Ali Girl, that's all that mattered!" Go, girl!

Teen Mom 2 airs Mondays at 9 p.m. EST on MTV.

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** Scroll through the gallery below for photos of Leah's body transformation!**