Cleaning Best way to get rid of odors in Midwest Cage

I'm currently fostering two piggies and changed their cage today because it smelled incredibly horrible (which is impressive because my cage of four hasn't even started smelling yet). I've been changed it every 2-3 days or so. They're house in one of the midwest habitats and the canvas piece it was smells so bad. I've washed it with soap (dye/perfume free) and vinegar twice today and it still smells bad. I have my baby pig in a separate midwest habitat and haven't had a problem with it, I usually wash it once every other cage change, which is about every week or so. All the pigs are kept on fleece, and spot cleaned once a day. I don't get how theirs smells so much worse than the other cages. Is there anything else I can do to try to get rid of the odor? Other than buying a new canvas bottom?