Calling all plumbers...again.

[Redsoxticket]

The grey water is probably being blocked due to a failure at the septic system. This will be more apparent during heavy rain where the leach field is soaked with water. Then grey water will then back up and leak at the weakest link.
and if no septic then same analogy with town sewer.

disclaimer: I'm not a plumber

[basswipe]

The leak was both the halfbath toilet and the vent stack.

The old copper pipe going up to the toilet had corroded away at the flange.It was replaced with some nice new pvc.Toilet leak solved.

I left the ceiling opened up before I re-sheetrock and compound it so some air could get up their and dry out the subfloor.Good thing too as it rainded today and I have a straight shot view of the vent stack all the way to the roof and yep there was a slow drip coming all the way down from the roof.