Where do you live? Has it been abnormally humid there? The black spots and leaves dropping look like humidity damage, mine are going through the same thing right now. We had five straight days of 90 degrees or more and 95-100% humidity at the end of September and they are suffering. This is my first summer growing them outdoors, I probably won't do it again.

Can I also say that I am very jealous of your plant? I hope mine are that big some day.

Thanks, it has looked better though! We're in Northern California. It was hot for one particular week and this plant has gone through similar weather in the past. Will have to keep monitoring it and see...

Outdoor growing does bring all sorts of spots. Hard to say what it is, though. Have you ever repotted or fertilised this beauty? if not, I'd say your soil is tired

I wonder about the soil as well. Is it in the same pot and potting mix that it was in when you bought it?