Mine drains through a hose left center (passenger side by the HVAC) near the firewall, and should be easy to trace and clearPerhaps the AC condensate drain is plugged and when that mouldy water is swished around it becomes more aromatic. Any mechanic should be able to clear it.
Do the reverse/tail light(s) come on normally? A flicker that could point to a loose connector, the insulation might be melting and may have caused the circuit to burn open now the resulting smell to stop.The car is pretty new...2 weeks old. And I didn't use AC too much.