Stinky shower in multi-story condo complex

[Tiffany H.]

Hi! We have a frequently stinky shower in a condo, usually in the pm. The smell is coming from the drain and we experienced this previously in a detached house. In that case a plumber determined that there was no trap so gasses come up. Crawl space under house allowed for a trap install and fixed the problem.

When I look in condo drain there's no water sitting so I'm guessing there's no trap. Problem is that underneath the shower floor = someone else's ceiling. Are there any easy fixes to this? Is there a product that can be inserted to do the job via the drain?

One more note, condo shower drains just fine.