Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain severe itching sensation all over the body that is lasting since 3 days seems to be caused due to severe Allergic Reaction or Anaphylactic reaction.. It can be due to causes like : -Certain foods out of which common ones are sea foods, nuts etc. -Certain Medications. -Contact Dermatitis caused due to certain soaps,detergents, poison ivy etc. I would suggest you to consult an Allergist and get evaluated and he can advise you allergic tests like get allergic tests like Patch test, RAST test, food challenge test etc can help in diagnosis and treatment can be done accordingly.. The tests will help in ruling out the exact cause of the allergen and once you know the cause of the allergic reaction you can avid exposure to it to prevent allergy attack.. He can be advised to take anti allergics like benadryl or Levocetrizine.. A course of oral steroids can also be advised.. In severe case steroid injection can be given for faster resolution.. He can also be instilled an Immunotherapy that will help in reducing the severity and frequency of allergic attack.. Once the allergen is ruled out avoiding exposure to it can prevent the allergy symptoms.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.