Do you have a picture of his rash? It could be heat rash if he do not have a history of eczema. Try to keep dry and as cooling as possible so as not to agitate it any further. You can use aveeno cream from kiddy palace to keep the rashes moisturised. If it is not eczema it should be fine using his normal body wash but if it is, you may want to change to soapless body wash.
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