Shaun Weiss -- best known for playing Goldberg in "The Mighty Ducks" films -- has reached the point of grave concern ... and desperately needs help before it's too late.
Sources close to the troubled 41-year-old actor tell TMZ ... he's currently living on the street and dealing with several life-threatening problems, including diabetes, mental illness and drug addiction.
We're told friends of Shaun's have been trying to get him into various rehab facilities for years now, but it's been difficult due to long wait lists ... along with his inability to stay out of trouble.