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This symptom 'black oily droplets' is a non specific sign. It is mostly due to a particular food item (like berries, nuts, heavy - fatty meals / fish etc). This will be difficult to isolate. If this is not occurring recurrently there is nothing to worry, you can just ignore it.
I assume that you do not have any of these symptoms like - sudden loss weight , recurrent loose black stools, vomiting, & abdominal pain
Hope this helps
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