 [ Symptoms ] my 3 week old granddaughter does not eat well or sleep well however she smiles widely when spoken too i saw an episode on mystery diagnosis that seems similar to her it was a while ago and i did not think much of it but i remember them saying the first clue was the happy infant that they were very young and it ended up being a rare and i believe neurological disease she does also have problems with her kidney tubes not developed fully and the ped was concerned she was not gaining enough weight in the proper time frame i cant find the episode to find the name of the disease can u help [ Disease ] does your baby take cow is milk i recommend testing s ferritin and tibc before proceeding with iron treatment thanks