I have no idea why my body is itching all over! Could it be from my houseguest?

Itching. During cold weather, skin is prone to dry out. This is the most common cause of generalized itching or pruritus. Another common cause is use of softener sheets in the dryer.. Try to investigate other causes like psychosomatic events, shampoo, soap, lotions, creams, clothing next to skin, medication taken orally or applied to the skin, sunscreen, insect repellents, etc.