sewer gas smell when using washer
 

We have an old house with two septic tanks. One of the septic tanks handles the washer, dishwasher and a toilet and sink. Every once in a while we would get the sewer gas smell in the bathroom when I washed clothes. I would aggressively use RID-X or something similar for a few days and the smell would go away. We attempted to get this septic tank pumped but could not find it. So after 15 years we finally found it and just got it pumped. It turns out this tank is under the laundry room in a crawl space. Well now the sewer gas smell is back and worse then ever. The RID-X is not working. I can't really tell where it is coming from. It happens when I wash and now when I wash dishes (we also just installed a new dishwasher). It kind of smells like it is coming from under the laundry room where the septic tank is but when I stick my head in the crawl space I can't smell it. We starated to think maybe it was a venting issue. So my husband put a hose down the roof vents to see if they were clogged. Now the sewer gas smell is even worse. It has been 3 days and we still have a lingering smell. At least before it cleared up in a few hours. Not sure what to do next or if it is a septic issue or a venting issue or what type of person to call.