The silver shiny layer is suggestive of Bitot spots which are an indicator of
Vitamin A deficiency. Give the child Vitamin A drops 50000 IU on Day 1,2 and 14. Start with eye drops refresh tears if the child rubs eye frequently. Also visit paediatrician for other signs of malnutrition. You need not worry about the black spot.
Next Steps
Consider online or physical consultation if no improvement.