Hello,
Since the itching is present over the whole body and that too without any visible rash, so I would like to rule out dry skin or xerosis in your case. Dry skin usually results from environmental factors that you can wholly or partially control. These include hot or cold weather with low humidity levels, long-term use of air conditioning or central heating, and washing or bathing too much.
Take some anti itch lotion and apply it all over the body. Also take some antihistaminic like Benadryl, take a comfortably cool bath and wear smooth-textured cotton clothing. You should choose mild soaps without dyes or perfumes and use a mild, unscented laundry detergent when washing clothes, towels and bedding.
If the symptoms persist then please consult a dermatologist.
I hope it helps. Take care and God bless.
This probably because you have the heater on and your body has a hot temperaturee. This don't happen in the summer right?