Hi, I recently had my bathroom renovated and in the past month or two I've noticed the wall appears to be blistering quite badly. Initially it was minor but it has gotten worse in recent weeks. The blistering is happening in just one place... by the side of the bath with overhead shower (with pipes in wall), which makes me concerned I have a leak. That said, there doesn't appear to be any discolouration, or signs of water damage in the room below. Any thoughts most welcome... Thank you!