Iron deficiency is one of the most common nutritional deficiencies in the USA and is especially common for children with autism. Iron deficiency may be caused by lead poisoning in children. Lack of appetite,grey teeth,change in skin color and lack of energy are symptoms of iron deficiency.
You need medical help for this and your child should be tested. Receiving iron supplements might be too hard for the digestive tract so try feeding iron rich foods. There are several SCD legal foods that are rich in iron:meat, poultry, fish, nuts,green leafy vegetables, and seeds(for advanced SCDers only). The food that contains the most iron is calf's liver and that is SCD legal. Try to get organic liver. Drinking bone marrow broths everyday should be very helpful.
Other supplements can also help. Ascorbic acid can improve iron absorption. Research has shown that high zinc and iron densities are positively correlated. Zinc may enhance the body's capacity to absorb iron.