you may have an allergy which
is sensitive for heating and temprature that maybe due to the response by your arms and legs cells incase they had get exposed for radiation or any other causes that damaged them.
From the symptoms neurodermatitis needs to be ruled out. Neurodermatitis develops when nerve endings in the skin become irritated, triggering a severe itch-scratch-itch cycle. Common causes of nerve irritation include an insect bite and emotional stress. I suggest you to get an examination done from a dermatologist. Also then get urticaria ruled out.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
My girlfriend and I had this same rash for about four or five months and stumbled across some information that made sense. There are lots of heavy metals in our air right now from the marshmellow snakes in the sky. When you eat gluten, these metals which we are breathing in are pushed out from our skeletal and muscular matter through our skin, which is what causes the itching that everyone is experiencing. Start taking borax. It is a naturally occurring mineral and it binds itself with heavy metals and pulls them from your system as well as helps regulate the hypothallamus, which is also responsible for the body's usage of minerals. 20 Mule Team is the common brand in U.S grocery stores. Start out with one eighth of a tsp dissolved in a litre of water and dranken throughout the day for five days a week. You may gradually increase the amounts after some time. You would need to eat at least a whole box of borax to overdose on it, though the taste is a little strange! Not only will this clear up your skin but it will also increase your energy levels, open your nerve pathways, clear your mind, improve your memory, increase the lucidity of your dreams, increase your sexual vitality, open your endocerine system, strengthen your bones and joints and elevate your mood! : )... Spread the word if you will!
Oh yes. And there is one catch... :( It will be necessary to stop eating gluten as well if you want to completely discontinue the rash since it is the gluten that carries the metals through the skin. This way the boron will instead carry the metals out through your urine. If this diet is too strict for you, take it up with your government, who are the ones spraying the marshmallow snakes in the sky (the lines of cloud that come from certain air planes).