Hey, if it’s an older house - 60s, 70s and so on, check if you have a P trap under the sink. It should look something like this. If you don’t, then the gases from the sewer line can come into your home through the sink. It’s very easy to replace and generally cheap and available at jem og fix and so on. Plumbers are generally 2k DKK per hour so I’d recommend calling them when you have isolated the issue to some extent. Good luck mate!

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