Answer: Based on your description I think your plant may be affected by scale insects which look like dark spots or discs on the foliage. These are often accompanied by black sooty mold type fungus growing on the sticky honeydew caused by the scale. They can be gently scraped off with a fingernail if not too numerous or you can treat with a commercially formulated insecticidal soap. Read and carefully follow the label directions. Once you treat the scale, the fungus should also stop. Be vigilant and retreat as needed to control them. I would also isolate the plant as scale can move to other plants in your collection.
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