HELP! My daughter dropped her sippy cup and it rolled under the seat. By the time I found it several days later, the milk had spoiled and spilled and pooled into the carpet. I have cleaned it so many times and my car still smells like rancid milk. I’ve tried: dishwashing liquid; baking soda; Oxyclean. My last resort was to open a home air freshener, which helps a little but when the car sits in the sun, the smell smacks you in the face when you get in! I’m starting to take public transportation to avoid it!
you may need to take it a professional, but I would think the padding below will need replaced, and the carpet cleaned while out of the car. Good luck