Can you remove foul paint in new construction to bare drywall?
Your choices are rip out and replace or add another layer of sheetrock.  I'm guessing the cause of the smell has soaked into the porous substrate  (sheetrock)  and will never come out.  I would advide using a vapor barrier unless you fully understand vapor and moisture control in walls though. From your tale personally I would sheet over the ceilings and rip out walls if it was just blown in above.