Ceiling Stains

Anyone out there have brown ceiling stains running down a section of their sloped ceiling without a roof leak? I have painted plank ceiling with a newer torch down roof. I have a section of the ceiling in the living that has brown stains running down it. I clean it and it just comes back.  I've had the roof company come multiple times to test the roof for leaks and nothing. It looks horrible and even drips on floor. Anyone has any idea what's going? Couls it be condensation inside the house? Happy to share photos if someoe wants to contact me at