Iching on whole body. What should i do?

Since last 2 months i am facing one issue. As i starts to take shower with water at room temperature generally cold, little iching starts on my whole body while shower only. Aftr the shower as i soak my body, Iching intensity increase and continues for around half hour. If i go under running fan just after shower it gets worsen. At the end i end up scratching myself. I have tried applying oil on my body while shower and moisturizer after after showr. It helps to some extent only. Even after that i feel Iching in many areas. If just after shower i hide inside blanket, it also helps me only if i have applied a lot of moisturizer and oils. Still Iching is there but i find it better option. From last 3 years, i go through same issues in winters if i use too hot or too cold water. If i get wet in rain and if its windy or i am riding bike i get red patches (like mosquito bite) on my screen and i feel lot of Iching. I don't know whom should i reach out to or what should i do? Please help.