I live in a two story split entry home. It has an upstairs and a basement. My restroom upstairs is right above the basement restroom. There is water leaking from the upstairs restroom down to the basement restroom. When we took a bath upstairs the water did not leak down to the basement restroom. It leaked through downstairs to the basement restroom when we took a shower. We are confused about what the issue could be. When we turned the shower on the water was dripping a lot onto the sink which cause the crack of the wall, above the light fixture and the ceiling to get wet. Any ideas on what could be causing this? I want to get it fixed as soon as possible before more damage can happen. Any ideas on the cost as well? In the picture you can kind of see where water damage happened. The wall became so sensitive we poked a hole through but just stuck a paper towel in to close it off for now. All answers are appreciated. Thank you!!