Any idea to what happen on my lo skin? This few days his stomach and leg has been appear reddish like this,could it be eczema or ring worm?

my baby boy has rashes on his face and back when he was 4 weeks old. ppl ask me to consult doc but seeing tat the rashes are not affecting his feeding or sleep. i decided to montior. i wipe him very diligently after every feed. But if you feel the rashes are really serious, pls see a doctor.