Our upstairs bathroom has a shower enclosure that we use every day. It smells bad like sewer. If I clean it with bleach, the smell is gone for few days but back again. The drain is not blocked. It drains freely. I assume I have to clean the drain pipe? The drain stopper doesn't look screwed-on. It looks glued. How do I clean such a drain? The house is 5 years old.
Thanks for any advice.