[fintstone]

Is there a vent from the garage to the roof or is there a bathroom drain that goes in that direction? I had a leak (and wet spot in the ceiling) once and it came from the other side of the house. ran down a rafter. There was a nail driven through the wall that had hit a drain line so it fluctuated based on which sinks/showers were used.

I also had a shower pan once that leaked and the water seeped across the room under the tile and carpet and was wicked up into a wall by insulation. Strange stuff.

Perhaps an exorcist would help.