What Causes Itchy Rashes On The Back, Lower Legs And Arms?

Hello Dr, My age is 40 years. Of late during this winter season, i have developed some sort of a rash on my skin especially on my back, lower legs, arms. Very itchy and are like small round circles. Once they are cured they pop up at a different place on my body. Not sure if they are contagious. Also they are leaving a dark purple scar / blemish on my skin. Will these patches be healed? Also as of now i am applying Lobate everymorning and night before sleep and apply bodylotion- aloe vera cream all over my body to keep it moist and supple. Please advice for apt medication / suggestions. ThankYou