Doug Kiker was rushed to the hospital after a involved passerby walked by him on the road … and, the star’s look was so worrying this individual known as paramedics.

Regulation enforcement sources inform TMZ … a person strolling round in Denver handed Kiker on the road, took one have a look at him, and instantly known as 911.

We’re instructed this individual instructed the 911 operator they have been frightened about his look, saying he might have been experiencing a drug overdose.

Emergency medical providers models transported Kiker to the hospital … the place he died 5 days later.

Sources near the scenario — not our regulation enforcement sources — instructed us medicine prompted Doug to have a coronary heart assault … touchdown him within the hospital.

Value noting … the medical expert has not introduced an official reason behind dying — and, the investigation is ongoing.

As we instructed you … Kiker’s ex-fiancée, Valerie Prepare dinner, instructed us Kiker died Monday — she stated she hated that her children misplaced their father. Doug’s mother and brother additionally confirmed his dying to us.

“The Singing Rubbish Man” rose to fame on Season 18 of “American Idol” … when he introduced Katy Perry to tears along with his rendition of Rascal Flatts’ “Bless the Damaged Highway.” He was eradicated within the following spherical after singing Marvin Gaye‘s “Ain’t No Mountain Excessive Sufficient.”

Kiker was 32.