Hello.

Thanks for posting the query.

I think it might be heat rash.The medical term being Miliaria.

If it is humid the sweat doesn't evaporate and the outer layer of your skin becomes soaked, swells, and the openings for your sweat glands close off. This causes a build up of sweat underneath your skin.
Most often heat rashes appear in covered areas: under your arms or between your legs behind the scrotum.

Treatment is to get into a cooler, dryer environment to slow down your sweating.
Switch to loose clothing of light material like cotton that will allow air to get to the area with the rash.

Body powders can ease the irritation caused by clothing rubbing on your rash.
Most heat rashes disappear in a day or so. If not use antifungal powder and consult the dermatologist.

Hope I have answered all your questions. I will be available for follow up queries if any.

Regards.

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