Q.What can I do for my sick, mature Yesterday-Today-Tomorrow bush?
It has a flaky substance that is white/mossy green on its branches. It is full of buds but they are never going to flower. It is starting to look like the trees in Georgia that have the Spanish Moss all over them. That’s where I live. There is no S.M. in this area. The leaves are turning yellow. The bush is 12 foot tall and about 12 foot around. The base of the bush is about 3 feet wide. This started about 7 weeks ago. My Hummingbirds haven’t been back for 5 days now. That’s when the bush was full. Now it looks like it’s dying really fast. PLEASE HELP! I can not send pictures.

It will be hard to say for sure without photos, but what you describe sounds like a fungal infection. I recommend adding dolomitic lime and wettable sulfur to the area around them. This will kill off infections in the soil, as well as keep the pH stable while this is happening.
This article will help you to care for these shrubs, otherwise: https://www.gardeningknowhow.com/ornamental/shrubs/yesterday-today-tomorrow/yesterday-today-tomorrow-plant.htm