Sewer smell

Check the vents are clear and the traps hold water.

What is in the tank should have no impact on what you smell inside.

Get a clear fitting. Dump, fill with some water, dump, fill, repeat until it runs clean. You will likely be amazed at how much "stuff" is left in the tank with just a simple dump. I have to fill/dump several times to get it all out. And before all the backseat campers ask, yes, I am using plenty of water to start with after a dump and during usage.

Quit farting in the bedroom....lol

Looks again. A plugged vent is my guess.

Might be a screw on vent cap under the sink thats not sealing.

You may have a vent that is pulled up out of the tank.
If nothing else, use chemicals to stop the smell.