Our home is eight years old. It's on a slab. This past spring we began noticing a sewer smell after it rains. Lately there is a hint of the ordor at all times. We hired a plumber, he could not find a anything wrong. We also had a leak test to check for plumbing leaks. The company did a smoke test and found nothing. I've checked the attic. I've walked around the outside of my home nothing appears to be wrong. There is a storm drain about 15 feet away, no ordors are emitted from it. I've contacted the city to come out and check. Our next option is to have the vents cleaned. I have a strong sense of smell. I'm in tears. Please help

Probably your best bet is to clean the vents and drains. It could be mold and fungus in them from dampness.