We have a large water spot in our kitchen ceiling that is directly below the stand alone corner shower in the upstairs bathroom. Any ideas on how to determine what is causing this?

A few questions first, Is this a plastic/ fiberglass enclosed shower or is it a custom tile shower? If you have a plastic base does it give a bit when you step into it? Since the spot's not dripping water we can assume this is a drainage issue, Answer my questions and I may have a solution for you. Back to you, tom