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.

Blood tonic, iron supplements and some iron rich foods causes black stool, but there is a need to see a doctor to rule out upper gastrointestinal bleeding.

U have to eat food rich in iron e.g snail, meat, fish, liver, vegetables, egg etc which will help improve d quality of ur breast milk, then u breastfeed him exclusively. Ask ur doc to prescribed an appropriate multivitamin for him so he can feed well. No formula will help u boost his PCV like ur breast milk. Also make sure ur baby sleeps under long lasting insecticide net to prevent malaria, cos malaria causes anaemia. All d best.