We're told Fetty and Alexis Skyy's daughter, Alaiya, needed the procedure to repair a malfunctioning implant in her brain that helps drain blood and fluids. Alaiya was born 3 months premature -- weighing just one pound -- and suffers from hydrocephalus, a condition that causes bleeding and fluid in the brain.

Sources connected to Alexis tell us she noticed something wrong on a flight from Atlanta to NY because Alaiya was excessively vomiting. We're told they bolted to the hospital where doctors began operating.