Hi, Welcome to Healthcare Magic, As per your query you rashes and itching on feet,arms and legs from last 3 weeks. There can be multiple of the causes for the problem which can be diagnosed properly by close examination or by detailed history or picture of the problem. The most important part is to stop scratching as this leads to the cycle of Itch- scratch and Itch phenomenon which can further aggravate the situation. For the betterment kindly follow the below: - Do not scratch any skin lesion or even try to touch unnecessarily. This is the most important part in your treatment. -Apply over the counter calamine lotion 3-4 times a day. -You can do cold water compresses to reduce the intensity of itching. -stay away from hot and humid climate. -You can take oral anti histamine like loratadine or levocetrizine round the clock under medial advise. - You can apply Fluticasone or mometasone cream under dermatological guidance. Despite above measures if the things are not better then it is better to consult a dermatologist for the best guidance. Hope to have provided the helpful informations regarding your problem. With good health wishes Dr Sanjay Kumar Kanodia MD (Dermatology & STD/Venereology)