Hi everyone! My husband and I bought our first house last year. It's a 20yr old house and needs a little work, but for the most part it's in good shape. Starting last year, in the cooler months, I began noticing random whiffs of rotten egg. It would only last 30-45min then disappear. We thought it was the drains, so we cleaned them, and checked p-traps. We thought we figured it out since summer came and the smell disappeared. Now it's cool again and our master bedroom randomly smells like eggs/sewer around 1am-3am. And early mornings right before sun comes up. The living room also smells sometimes. My hubby and I are very clean (OCD clean). So it's not old trash etc. I've searched online tirelessly but can't seem to find exactly what I'm looking for. We don't have a septic system and have checked p-traps. It's not an ongoing smell, it comes a goes. I sometimes smell the same smell through out the neighborhood when we walk our dog at nights. Is it dangerous? Also, how can we fix it?