Cannon, who is married to singer Mariah Carey, was hospitalized for kidney failure in January and blood clots in his lungs in February. The 31-year-old father of toddler twins is host of "America's Got Talent."
Last month, he announced he was giving up his daily morning radio program after doctors suggested he ease up on his workload.
"The blood clot thing was probably the scariest because ... I've known people who have passed away from that," Cannon told People.com. "I thought I was getting better and then that happened, so that kind of came out of nowhere."
Cannon said his kidney condition is an "autoimmune disease that [doctors] found in my system" and something he is going to have to live with all his life. He said his blood clots were directly connected to his kidney problems.
"I'm just trying to make sure I put my health first," he told People.com. "It's a lot of stuff, but it's all in order now. ... They kind of say [my] autoimmune [disease] is -- like a lupus-type of thing, but no one else in my family has it."
Celebrity Families of 2014 [PHOTOS]