Hi. I've had this funny smell coming from one of my bathroom sinks for a while now. There are two bathrooms upstairs I don't use one but I run water daily in the sink and I flush the toilet. I've taken off the elbows underneath both sinks clean them and there were no blockages there or any kind of stuff that would make a smell. And it won't go away. Someone told me maybe the vent out through the roof is clogged. Can you help? Thank you

try pouring some bleach down the sink overflow hole.

I've poured bleach down, vinegar and baking soda, peroxide and Drano. None of it helped.

into the overflow hole ?

Yes. I poured the bleach in the overflow I poured the Drano in the overflow pipe for the peroxide in the overflow and I took the baking soda and put it down the drain and then poured the vinegar down and it came up through the overflow like they said it was supposed to. I have no idea where it's coming from