Is there a particular dietary deficiency causing fatigue and lethargy in my child?

Yes. There are several nutritional deficiencies that can cause fatigue and lethargy in your child. Iron deficiency can cause anemia, which can lead to paleness, tiredness, and difficulty keeping up with the other kids. Certain vitamin deficiencies can also cause fatigue. It is important for your child to have a balanced diet to prevent these nutritional deficiencies.
Yes. Many dietary deficiencies present with fatigue and lethargy, but so do many other illnesses. Persistent fatigue and lethargy is so unusual in a child that you should check in with your pediatrician as soon as possible, rather than delaying proper intervention trying to find the nutritional solution.