Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain rashy hives on the face and scalp with severe itching seems to be most probably due to allergic reaction and in case if you have not changed any medication, shampoo, soap or laundry etc then it seems to be most probably due to any food.. Other cause can be Mite Infestation causing Scabies.. I would suggest you to consult an Allergist and get evaluated and a thorough clinical evaluation and investigations like allergic tests like Patch test, RAST test, food challenge test etc can help in diagnosis and treatment can be done accordingly.. The allergist can advise to oral anti allergics as well as injectable steroids for relief.. In case of Scabies you can be advised Oral intake of Ivermectin and topical application of Premetherin ointment.. Washing all your clothes and bed sheets and putting them in sunlight along with mattresses should be done.. As of now you can take anti-allergics like Levocetrizine, Allegra to control the itching and swelling.. Do cool compresses.. Application of calamine lotion can help in soothing the skin.. Hope this information helps.. Thanks and regards.. Dr.Honey Nandwani Arora..