Allergic dermatitis is more likely to give you the rash with perhaps a small blister involved. There is an intense itch/burn feeling. Common causes would be latex, nickel, perfume, cosmetics, hair dyes and weeds such as poison ivy. I would particularly consider latex if it is around your bra or underwear line. You may also be using a different cosmetic or just have developed a sensitivity to one you have used for a long time. Shingles only occur in someone who has had chicken pox in the past. It is usually preceded by episodes of pain or tingling in a limited area, usually only on one side of the body or face; usually, blisters also develop, but not always. I would especially consider this as the probability if you have areas of pain and others that seem almost numb.
If it is shingles, there are medications that your doctor can prescribe that can help them go away faster. Since it's on your face, it is especially important to get this treated, as it can spread to the eye. If it seems to you more like an allergic dermatitis, benadryl oral or topical should help with the itching. Any rash lasting longer than a week, blood red or purple in color, around the face, or increasingly bothersome, should be checked by a physician.
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