10:40 AM PT -- Janice's manager tells us she's been battling a combination of bronchitis and lupus and the blood clot was actually in her lungs.

9:20 AM PT -- Miley just posted a photo of a rainbow with a tribute to Janice.

"The Voice" singer Janice Freeman -- one of Miley Cyrus' favorites on the show -- died Saturday, from an apparent blood clot ... TMZ has learned.

Janice's family tells us she was at home in West Covina with her husband, Dion, when she started complaining she couldn't breathe. Dion called 911 and had to perform CPR on her until paramedics arrived. She was pronounced dead around 5:30 PM at a hospital.

We're told it appears a blood clot had traveled to her heart. Janice had a slew of serious health issues, having battled lupus, cervical cancer -- which she'd beaten -- and meningitis.

The singer went deep into season 13 of "The Voice" back in 2017. Janice was on 'Team Miley' and made it to the top 11.

She and Miley stayed in touch after the show. Back in 2018, Janice posted a very emotional thank you to Miley for helping her out financially when she and her family were searching for a place to live.

Janice is survived by her husband and daughter. She was 33.

RIP