Baby’s skin

Hi loves my baby boys got a kinda rash all over his body it’s really bad on his back u can’t really see much cause if his skin tone but it feels like sandpaper it’s so rough the nurse said it could be sandpaper skin and it might just be his skin type I’m not believing that for a second cause it appeared out of nowhere its starting to spread to his face I’m so lost the doctors he’s registered at are so useless all I’m ever met with is I think or it’s probably I didn’t go to the doctors for a stranger to look at my child and have a guess does anyone know any good creams or oils ?