Hi You have not mentioned about the age of your son. Usually contact dermatitis presents with a rash that itches. Scabies has to be ruled out. If your son has generalized dry skin, chances are there that winter will cause exacerbation of his itching. In such a case, he might need to keep his skin moist- with good moisturizing lotions like cetaphil lotion and cetaphil soaps. In addition he will need anti-histamines like Cetrizine/ Allegra- in right dosage according to his body weight. If symptoms persist, its better to consult a Dermatologist. Hope my answer helps you. Best wishes.