I have a tiled shower that has leaked on the ceiling below. I have already reseated the drain. The grout appears to be OK. There is a small hole at the bottom of the tile by the shower pan about 1/2 inch wide and water comes out into the pan when shower runs. I have cut holes in facing wall and no leak can be seen from the plumbing parts. Any idea what this hole is, or where the water might be coming from?

Take a picture of it and post it for us to see... Back to you... Milo