I have a very unusual problem. On the left and right side of my shower cubical on the outisde walls where they are bricked in the bricks just in the mid centre of the wall (only) are getting a damp and bobbling patch. I have no idea what could cause these isolated 'damp' patches on the brickwork. Could there be leaking pipes cemented behind the shower cubical in the brick work stretching left and right? But why would they just soak a couple of bricks in the centre of the wall each side as there is no trace of damp top or bottom? I'm just trying to save having to knock down the brick walls to see where the trouble is coming from. Could it be something to do with there thermostat which I just recently change a couple of weeks ago? I would appreciate any advice.