Does any mummy here know what is this white spots/patches on baby’s chest/neck?

Hi mummies, my baby is 1month plus and i found out she having these white patches around her neck and chest area. Brought her to PD and polyclinic and the doctor can’t advise what is this and only told us to keep these area moisturised. Can any mummy here advise me? first time mom here and im quite worried as it seemed to be spreading.