lets see a picture of your cage. Do you have substrate in the bottom which could be molding? Do you have live plants? If so, they could be getting water logged and the roots could be starting to rot. Do you have a dripper? If so, try and position it so it does not constantly drip in the plant or plants.
Proper drainage and ventilation is the key. Cage should "dry" between mistings also. Other factors can include live plants having too much water in soil and poop sitting in moist or wet bottoms of cages.