How can I treat my skin rashes that occur on my face and neck due to summer heat? Is there any home remedy?

During the summer and moonsoon season my face and neck is full of red spots(gamordiyan). It not only looks ugly but is also vey irritating and painful. The moment I step out in the sun there is huge burning sensation followed by thse ugly and pinching red spots. Despite taking so much of Homeopathic and Ayurvedic medcine and tal and heat powders there is no relief. I also take a lot of water now as suggested by my friends. If there is some other remedy please suggest me. Thanks and regards.