J.B.
Something similar happened to us and thank God we caught it in time. It was electricity burning. Every time we used a certain outlet this would happen. We finally noticed a burning spot on our wall, felt the wall, and then called 911. We then had a electrician come and fix the outlet and no more smell.
It would smell when we used our dishwasher and we would wonder if it was the dirty dishes. It smelled like a fishy odor sometimes. So I would check the outlets that your washer and dyer or plugged into.
Hope this helps
J.