Hi Welcome to the HCM I have gone through your question. As per your description, it seems that your child has miliaria crystalline which occurs due to blocked sweat glands. It occurs more often by oils when applied during hot weather. No compelling reason to treat miliaria crystallina exists because this condition is asymptomatic and self-limited. The prevention and treatment of miliaria primarily consists of controlling heat and humidity so that sweating is not stimulated. Measures may involve treating a febrile illness; removing occlusive clothing; limiting activity; providing air conditioning; or, as a last resort, having the patient move to a cooler climate. Topical treatments that have been advocated involve lotions containing calamine, boric acid, or menthol; cool wet-to-dry compresses; frequent showering with soap. Hopefully this will help you. I will be happy to help you in any further child health related questions. Take care