the pipe to the drain probably needs a vent pipe up above the roof - if it has one already it may be blocked by a birds nest or similar. malj.

I had a similar problem but it wasn't the drain. I didn't have tile, but some solid surface for the shower floor. Water seeped in under it and caused it to smell. Once I re-caulked everything (drain, walls, etc.) it stopped smelling,

Try dumping some baking soda down the drain, leave it sit for a few minutes, then flush it out. If the smell remains, it's not in the drain pipe itself, but somewhere else. In fact, if bleach didn't help, I don't know that the soda will either, but it doesn't hurt to try.

It's possible that you don't have a p-trap in the drain. P-traps (like the one under your kitchen sink) retain some water in the bend to block air from coming back up the drain. Specifically, sewer gases, since all your drains are connected. If you have access to the underside I'd check for that.

I'd second the P-Trap comment. Gases from the sewer come back up without that U shaped pipe underneath.

If there is a toilet on the same line and they are both not properly vented. When the toilet is flushed it can draw air from that shower drain causing the trap to go empty, or spill sewer gases as it takes air in through the drain. I have even seen it happen in Montana, where the vent pipe freezes closed up on the roof and the volume from a toilet flush will draw air from the shower drain.

Cover after use.