Hello dear patient itching can be due to allergic reaction to some food material or allergen. You need to take medication for this. Take a consultation.

It is likely the whole body itching occurred due to an allergic reaction to either food, environment or to some material. Kindly keep an eye and see when this occurs, apply calamine lotion over the rashes and visit the nearest ER at the earliest when this occurs so as to take the injection to normalize the situation. You can undergo an allergen test which could help with finding the allergen.