cannon022812_08_X17230pic.jpgNick Cannon is ready to talk about his severe health problems ... as well as why he was hospitalized two months ago for kidney failure.

Mariah Carey's 31-year-old hubby tells People:

    "The blood clot thing was probably the scariest because ... I've known people who have passed away from that. I thought I was getting better and then that happened, so that kind of came out of nowhere."


Cannon says the kidney failure was a result of an "autoimmune disease that [doctors] found in my system."

The father of two recently took a break from his NYC radio show due to his medical issues.