Hello and hope you are doing well.
Itchiness of the whole body could be due to extreme dryness of the skin or due to jaundice. It could be due to iron deficiency anemia, liver and kidney disorders, thyroid disorders, polycythemia, diabetes and malignancies (cancer). It could also be due to certain medications and food. Others could be due to skin conditions like contact dermatitis and scabies. In contact dermatitis exposure to an irritant like a chemical or metal or anything you are allergic to, can cause rash and itching. Scabies infection is caused by a mite Sarcoptesscabiei, it burrows in the skin folds of hands and feet and causes intense itching mostly at night. You may need to consult a your doctor who will examine you and may ask for blood tests and in addition examine the scrapings from the skin to arrive at a diagnosis for appropriate therapy.
Hope this helped and do keep us posted.
Why don't you try an antihistamine cream like Benadryl or something like that?