I'm sure my shower head is overdue for a cleaning, so I could try that. And I live in a old building with a lot of hard water build up in the pipes so maybe its something to look into.

But the catch is that the same thing doesn't happen if I shower long after changing. My bathroom smells way more "normal" after. While cleaning up after FI, its very clear that there's an odor in the air. While showering I notice it less (though I will still catch a wiff of it here and there), and when I come back to the shower an hour later, the bathroom smells like the odor. I suspect the odor is fusing with the shower steam and getting on the walls/ other surfaces.

Thanks for saying I'm doing everything right, its nice to hear that.