Toddlers dry scalp

Hi! My almost 3 year old’s scalp has been pretty dry the last month or so. It’s not cradle cap it looks more dandruff like.

He has no allergies and we’ve been using the same soap since his first bath as a baby - tubby Todd. My 5 year old uses it too and has pretty much since he was 1 and has never had any issues.

Any suggestions what I can do to help it go away? Also now thinking I need to switch soaps. Any recommendations on that?