Welcome Beth. Hope we can help.
Have you checked the backs of the leaves for insects? Might want to use a magnifying glass for spider mites. Soapy water is the solution for those,1/2 tsp. Per quart of water.
Spray a couple of times per week for a while, and be sure to hit under sides of the leaves.
Could you post a pic of the whole plant or plants? They are fairly vigorous and might need repotting. Also just turning the plant out of the pot can give you a good indication of over watering.
