Sour Smell After Every Shower

[NJHomeowner]

After each time we use our shower (2 - 3x/day), a SOUR smell emerges - not sure if from the drain directly or somewhere else. The shower is enclosed, though we have a window in the bathroom. See example of the style (not the actual shower).

It can be a faint or strong smell, depending on the day. I tried the vinegar/baking soda/water home remedy, but it didn't seem to do the trick. The smell can be so bad that in addition to our exhaust fan, we'll have to crack our window open.

Is this something that has to do with the maybe the P trap, or do you think this is a mold problem below the shower? It's a tiled bathroom - roughly 11 years old. We do get spot bits of mold here and there on the floor in the corner/seam, but it is easy to clean and is cleaned up quickly.

Any help would be so appreciated!

 

[Electroguy]

My first thought is to scan the shower area with either a good quality moisture meter and/or thermal camera. I know those tools are expensive, so it would make sense to see if you can borrow them, or find someone that has them and is willing to come over to check it out for a relatively low cost. The point is to check to see that you don't have a serious water leakage problem into unwanted areas.
If that checks out, then the smell would almost surely be coming from the drain. It could be that there is an issue with the trap either being sucked out or positioned so that there isn't a water seal anymore (or maybe there isn't a trap?).

 

[Geofd]

has this happened from day 1 or is this something new??????when you look into the drain do you see water???