Hi.. Rashes on the face and neck with some itching seems to be most probably due to allergic reaction that can be due to any food or medication.. I would suggest you to consult an Emergency room and get evaluated and a thorough clinical evaluation can help in diagnosis and treatment can be done accordingly.. Allergy test can be done for confirmation.. 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 avoid exposure to it to prevent allergy attack.. The allergist can advise to oral anti allergics as well as injectable steroids for relief.. 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 I have answered your query. Let me know if I can assist you further. Regards, Dr. Honey Arora, Dentist