Hello, heat rash usually occurs around the neck and chest and face. It is a reddening of the skin, uniform in colour and not spotty. There isn't usually any raised/bubbling bits and it isn't painful or itchy or irritating. It will resolve in a short period of time on its own once you cool down. What you describe doesn't sound like heat rash but if it concerns you and it is bothering your child maybe you should take them to your GP just to make sure everything is ok. HTH.