The former basketball star was found unresponsive in a Nevada brothel one week ago and has remained in hospital ever since.
He was transferred from Vegas to LA this week.
According to reports from the US, the estranged husband of Khloe Kardashian has undergone two emergency surgeries in recent days.
A source told People that one surgery was connected to pneumonia that Lamar, 35, developed following his collapse, and that its taken its toll on his body.
"Lamar is in a very fragile state," said the insider. "The infection, that is being aggressively treated with strong intravenous antibiotics, is unfortunately not getting better. There are many concerns about his health."
Another source told TMZ that the surgeries have left Lamar in "a fragile mental state" and "very upset" at times.
It's alleged all visitors bar Khloe, 31, have been banned.
Despite splitting in 2013 and filing for divorce, Khloe has been at Lamar's side since the day of his collapse. They called off their divorce this week.
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