It could be heat rash, maybe wear looser clothes and place your infant in a cooling room? In case it’a heat rash - use normal temp water, try to avoid warm water cause it may aggravate the skin. Alternatively, you can try using lovera magic jelly baby! To cool down the skin. If all these dont work or you see no improvement, better to bring to see a dermatologist who specialised is paeds, I know one who works in Mount E Orchard Dr Shanna Ng. You can use CDA if I’m not wrong