Should I use vinegar or bleach for rotten egg smell in 36ft holiday trailer

Today we noticed the drain our washer empties into was backing up. My husband poured drain cleaning into it but it did not help much, after about 8 hours he repeated the same procedure, shortly after I notice a fowl smell like rotten eggs emiting throughout my house is this cause for concern?

I live in an highrise apartment unit. I have a terrible sewer smell in my bathroom. After letting the water run for a while I think it is coming from the bathtub drain. The drains is not clogged up and the water is running out very well. I have tried the bleach - hot water thing, taking a bented...

When I turn the air conditioner on after being off for a day or so I notice a rotten egg smell for the first few minutes the air is on. What is causing this smell?

I have well water with a rotten egg smell, from what I am told it could be the anode rod in the hot water heater. I don't have a hot water heater, we have a hot water boiler that is used to heat the house and the potable water, also is the water dangerous due to the smell.