Kindly note that when their is a need to check your child's iron level in case of anemia, the attending doctor will refer you for the test based on his evaluation. But if you are just worried about the iron level, you can still see a paediatrician for evaluation.
Meanwhile since malnutrition is one of the causes of anaemia, ensure you feed your child foods rich in iron, folic acid and vitamins as well.

Pyelonephritis is infection of the kidney and it is something that can be fully treated. As long as the child did not suffer any kidney damage during the illness, there is no need to worry.

However the child will require follow up by a Paediatrician - Paediatric Nephrologist preferably.