The pump on the dishwasher was leaking ...nothing too drastic. It's hard to know how long it had been leaking. There is minor swelling on bottom of cabinets. There is no water now under the cabinets. We also pulled out the new dishwasher. It seems like the smell must be coming from between the back of the cabinet and wall or in the wall itself. We will try the bleach and water on the areas we can get to.
The diswasher connects the same as yours ...through the garbage disposal. We had service dealer come out and they said it was plumbed correctly and that it couldn't be coming from the dishwasher.
We thought if it was sewer fumes we should smell it coming up through the sink but don't know if that would necessarily be true.