This is a bit of a long shot but hopefully worth a try.....
I've painted the walls of a bedroom with a bad batch or Dulux Emulsion which caused a sour odour once fully dried (walls had been freshly skimmed and paint didn't smell in the tin). I was advised to wash down the walls with bleach and...
I reskimmed and painted my daughter's bedroom 6 months ago and have been left with an unpleasant sour smell which won't go away. After a lot of research and trial and error I believe it to be 'Wall Odour Phenomenon' as I used a brand new tub of Dulux Matt Emulsion. The paint didn't smell off...