Sweet smelling bathroom / VOCs?

Hi — I am on the hunt for the source of a smell in my new addition. There’s a bathroom on the first floor of the addition, no bathroom on the second. The bathroom has a persistent sweet smell that started about 2 weeks ago (a few months after we moved into the addition). In the bedroom adjacent smells sweet/sour/sharp - like VOCs emissions. Same downstairs. We got 2 VOC monitors in the bedroom and they register above average VOCs when windows are closed. Sweet smell is in the walls. We’ve been thinking something started suddenly off gassing when weather turned warmer. But someone on another sub mentioned the sweet smell could be sewer gas. Any thoughts greatly appreciated! We’re going crazy trying to figure it out!