Medicine Wheel Lyrics

Lyric discussion by corich 

Cover art for Medicine Wheel lyrics by Aimee Mann

I think it's a mother addressing her drugged-out ex, who is reduced to holding up a cardboard sign and panhandling under a bridge. She's upset because the bastard is corrupting their son now. But I'm not real sure about any of that. It's not Aimee's most obvious song. Anyone?