Bushwick Bill Spent Final Days at Colorado Holistic Facility

Geto Boys rapper Bushwick Bill turned to alternative medicine in his final days, and he went to the Mile High State to find some peace of mind before his death ... TMZ has learned.

Sources close to the hip-hop pioneer tell us Bill passed away Sunday night in Colorado. Our sources say Houston was relayed to the media to protect the family's desire for privacy. We're told BB had checked into a Houston hospital in late May -- but when doctors said he could catch a blood infection due to his deteriorating immune system ... he opted to head for the clean air of the Rockies.

We're told Bill decided to try holistic treatments at the Colorado facility where he checked in late last week. It was exactly the kinda setting he wanted -- in nature surrounded by majestic mountains.

As we reported, he died Sunday with his kids by his side after a hard-fought battle.

BB was able to tie up some last-minute business as well -- we're told he was able to finish his final album, "Check Morals/Turpitude Balance" and also put the final stepping stones in place to launch a Pancreatic Cancer Foundation.