We had a musty smell in our carpet after we got them cleaned. The smell got worse over time. Two months later I called in another company to clean the same carpets and the musty smell is still there. The new company even used a deodorizor and it still smells. We decided to tear up the rug and see what it is. Thee are stains on the bottom of the rug (backing) throughout the room. Anyone know what this might be? Cheap carpet? Water stains?

Thanks in advance