Teen Mom's Leah Messer and Corey Simms are still searching for answers on their daughter Aliannah's developmental delays.

On Tuesday's all-new episode of MTV's reality hit, 2-year-old Ali undergoes her second MRI procedure, but the pain of having to see one of her twin daughters sedated is more than Messer, 19, can bear.

Keeping calm as she and then-husband Simms, 21, speak with the anesthesiologist caring for their daughter, Messer even goes into the procedure room to keep Ali's mind off the sedation process, which also includes having a breathing tube inserted.

"Ali, I love you, okay?" the concerned mom tells her daughter before being sent out of the hospital room. Later, Messer breaks down in tears on the shoulder of Simms.

Messer tells Us Weekly that doctors have high hopes for Ali, who, like her sis Aleaah, is starting to speak in full sentences.

Says Messer, "[Ali's] already walking on her knees."

Teen Mom 2 airs Tuesday at 10 p.m. (EST) on MTV.