How do i "stimulate my babys bone marrow into producing more iron"?

I dont know if many people will be able to help with this but my 7 week old baby was born with hereditary spherocytosis (a spleen disorder affecting red blood cells causing anaemia and jaundice). He has got it from his father who has it all through his mums side of the family. He has been admitted to the hospital twice now as his haemoglobin dropped dangerously low making him very anaemic and lifeless basically. They have considered a blood transfusion but dont want to do that until things get REALLY bad. He has been put on folic acid (5mls a day) which he will be on for the rest of his life. I took him back to the gp the other day as he was very white again . Hes a bit more anaemic apparently. The gp said we need to try and stimulates bone marrow into producing more iron? How can i do this? And hes only 7 weeks so obviously only on milk so i cant yet give him any foods with iron in yet. Any input would be appreciated alot about giving my baby more iron or naturally making his body produce more? Thanks in advance .