[Ryan57]

Prince was treated for a drug overdose 6 days before his death ... multiple sources tell TMZ.

Multiple sources in Moline tell us, Prince was rushed to a hospital and doctors gave him a "save shot" ... typically administered to counteract the effects of an opiate.

Our sources further say doctors advised Prince to stay in the hospital for 24 hours. His people demanded a private room, and when they were told that wasn't possible ... Prince and co. decided to bail. The singer was released 3 hours after arriving and flew home.

We're told when Prince left he "was not doing well."

His autopsy will take place later today.