my baby also got eczema though on full breast milk. It started at around 3 months old.
I also do not know whether it's due to my diet. But somehow I do not eat shrimp, crap, beef....
my bb also got some red spot or somethng like 粉刺 on his face? is your bb having something similar? Doctor said that they are not 濕疹. My anutie said that it is because my milk is "hot". I use "gold/silver chrysantheum" to wash his face and they are gone.