Greetings,as you mentioned you are suffering from Prickly heat(miliaria rubra) normally is an itchy rash of small, raised red spots that causes a stinging or prickling sensation on the skin. Prickly heat can develop anywhere on the body, but it usually appears on your face, neck, back, chest or thighs a few days after exposure to hot temperatures.and treatment will depends on the condition ,without seeing can't say much more .You may can get in touch with me for further.Regards Dr shuhaib (Pune)