Certified GKH Gardening Expert
This is normally indicative of some type of environmental change, but yellow spots usually mean the plant is being deprived of nutrients. I would first reduce any watering, as over watering is one of the most common causes of leaf yellowing. You should also increase the fertilizer, should the plant be nutrient deficient. In addition, nutrient deficient plants may be a sign that it's in need of repotting. Are there any roots coming from the pot? How is the light where the plant is located? A change in light conditions can also trigger this response. Is it too drafty? You may need to move it. Finally, check the plant for pests. If necessary, you can treat it with neem oil, which should take care of any pest issues and as a bonus, it's also a great fungicide.