Talk to Dermatologist on Heat Rash

I have a very severe heat rash. I’m also eating cooling foods. I’ve used prickly heat powder and even applied ice, but it’s not going away. There’s intense itching, like needles pricking me. The powder gives relief for a few minutes, then the irritation returns. It’s mostly on my back, arms, neck, and face. It’s so irritating that I feel like crying, I can’t even offer my prayers. When I cover myself with a dupatta, it immediately causes a stinging sensation, so I take it off and just lie under the fan—I’m unable to do anything. My sleep is disturbed too. It’s been four days—please tell me what I should do.