Hi, we had a very similar problem. Every time the shower used, a smell of solphur, or worse. It would go through whole house. On private well so "shocked" (disinfected) well and pipes. No joy. Solution was simple. Previous owner thought he could do DIY!! He connected electric shower in the bathroom. Problem was, it wired dangerously. My daughter broke off pull-chord switch by accident and when I opened housing, Bingo, there was the smell. Solphur/urine smell. Plastic burning through. Worth checking wiring if you have a shower, VERY dangerous. New unit installed and have had no bad smells since then. Hope of use to you.