updated 05/19/2011 AT 5:30 PM ET
•originally published 05/20/2011 AT 12:45 PM ET
After a long history of health problems and addiction, Taxi star Jeff Conaway fell into a coma a week ago in Los Angeles.
The latest crisis for the troubled actor, 60, came as a surprise to those closest to him.
“He seemed fine early last week,” his manager of eight years, Phil Brock, told PEOPLE on Thursday. “He had spoken with his agent and his management team and even attended an autograph signing. He really seemed in fine spirits.”
Given what appeared to be a content state of well-being for Conaway, Brock and the rest of his team were devastated when the actor was found after lying unconscious for approximately 10 hours.
“We strongly hope for his recovery,” Brock says. “We hope he can finally exorcise the demons that have plagued him. He is an amazingly kind soul and there are many people who care about him.”
Brock fears the ultimate outcome of the situation – and for good reason.
“Over the weekend, there was head movement, but there have not been any changes in his movement or condition since then,” he says. “We are concerned it may have been an overdose but we have no way of knowing for sure.”
Conaway, who battled substance abuse since he was 17, had an open struggle with alcohol, cocaine and pain pills over the course of his life.
At the time he slipped into a coma, Brock says the actor was on a combination of legally prescribed painkillers to treat back problems and other medications for various illnesses. The adverse reaction caused Conaway to come down with pneumonia.
Conaway’s problems were publicly addressed on Dr. Drew Pinsky’s Celebrity Rehab reality series on VH1, during which Pinsky told PEOPLE the Grease actor was “complicated,” but “not hopeless.”
“I am deeply saddened to learn of Jeff’s condition,” Pinsky says of Conaway’s current state. “My thoughts and prayers are with Jeff and his family.”
With additional reporting by CYNTHIA WANG