its tough to tell without looking at the lesion but you symptoms suggest you may have psoriasis
in this condition lesion is very itchy ,after scratching you will see white powder like flakes, this condition becomes worse when your in stress
, then summer time. you will have to visit a dermatologist
..he will inspect the lesion and guide you further.
till then you apply moisturizing lotion on it and take antihistamine for the itching.