I've had an umbrella plant for nearly 10 years. The last several months I've watched leaves either turn completely very light color and fall off or the ends of leaves turning brown and then further deteriorating. Also, once the leaf falls off there is sometimes browning down the center seam of the leave and blotchy leaves. What suggestions are there? I don't think it's scales as the pictures I've seen don't look like what I have going on. Thank you.