This is my first time growing any kind of vegetable plants, and I'm growing zucchini in containers. They are just beginning to flower, they are about 9 weeks old, and they have actually been doing great. I've put a ton of research into how to properly grow them, but in the past week they have developed many small yellow spots all over the leaves, which seems to be taking over all of the leaves now. They spread out over the entire leaf, and then turn grey/silver. Once the spots turn grey the leaf begins to crumble away, and I haven't seen any kind of recovery; it only gets worse, and worse.
I've googled and searched everywhere online, and I can't seem to find any disease or problem quite like this. I cut most of the really bad leaves off, but more yellow spots are invading fast.
Does anyone know what may be causing this? I've attached a photo of an infected leaf that I left on the plant. In a few days these leaves will most likely be fully yellow with tiny spots, and they will turn silver/grey, and die. Any help or advice is greatly appreciated! I should also mention I'm only growing them organically. Thanks in advance.