Thank you very much for the useful information.
This is most likely a result of allergic reaction (one can have allergies to number of objects like garments, bed sheets, environmental pollutants, pollens, dust, insect bite or even to some kind of foods.
A fungal infection of the skin can also be the trigger.
Benadryl is fine, but you may require topical steroid (1% hydrocortisone) along with anti-fungal cream (available over the counter) to be applied over the affected area of skin.
For throat, gargles with luke warm water.
All will help.
If the problem persist, does not improve or gets worse, see you doctor for further evaluation as this may requires prescription strength anti-inflammatory drugs or even a course of antibiotics for you throat (if required).
Stay adequately hydrated.
Keep your skin dry and clean.
Use only pure cotton clothings.
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