Former "Celebrity Rehab" star Shifty Shellshock is currently in a coma in an L.A. hospital -- TMZ has learned.
According to sources, the former Crazy Town singer has been in the ICU since last Thursday and is completely unresponsive. It's unclear what put him there -- but people close to him believe it was drug-related.
Shifty is scheduled to appear in court this week for a pre-trial hearing -- after his February coke arrest. We're told he was extremely anxious about the possibility of going to jail.