It all began five years ago when they noticed a light spot on the face of Cori, then 6 years old. Weeks later, the daughter of Snoop Dogg and wife Shanté Broadus was losing drastic amounts of weight and her hair was falling out.
Despite visiting countless doctors, no one was able to offer the rapper and his family a diagnosis for little Cori. "I felt helpless," Snoop told PEOPLE while fighting back tears. "No power, no friends."
His wife Shanté adds, "No one could tell me what was wrong. They drew tons of blood and said she has old-person cells. They gave her all kinds of [medication]. But she went downhill."
Months later, after getting the heartbreaking diagnosis of lupus, Snoop Dogg and his family began their journey to understand the autoimmune disease, which ultimately brought his family closer together.
"She's the toughest little thing I've ever met," the rapper says of his daughter. "She's on the honor roll, playing volleyball and softball, living life. She has all this joy. In the beginning lupus was winning. But now Cori is."
For much more on Snoop Dogg and his family's united front against lupus, pick up the latest issue of PEOPLE, on newsstands Friday
To learn more about the disease, visit LupusLA.org