The singer's wife, Lucie Zolcerva-Grimm, says Michael has been hospitalized since Memorial Day and remains unconscious, though he's finally breathing on his own again.

Michael's wife says the root of the issue is not clear ... but he had not been feeling well for a while, lacking energy and having a tough time finishing his recent performances.

She says things reached a head last month when he became increasingly sick. Michael's wife says he could barely walk and couldn't lift his head, so she rushed him to the emergency room, where things got worse.

Michael's wife says his blood pressure skyrocketed when he got to the ER and he started talking gibberish, so he was rushed to the ICU ... where he remains.

Doctors put Michael on a ventilator and sedated him, his wife says, and he's only recently been taken off the ventilator ... though he's still sedated.

Michael's wife says most of his upcoming shows this month have been canceled ... noting he will not only need to regain consciousness but also undergo physical therapy because he's been bedridden for over a week.