2004 Pontiac Bonneville stink in CAB

I think something is dead in my blower motor. Turned on the fan last Saturday it sounded like it was broken. We were out of town at the time and could not take a look at it. Drove Sunday and Monday with out using the fan. Today I got in the car and it just reeked to the point that you couldn't stand being in the car. There were flies flying around the inside of the car. (I had the windows shut so they came from whatever is in there) We took the blower motor out and cleaned it, but car still stinks. Where else can we look?