L.K.
It sounds like it might be an allergy - I am allergic to corn and get the same kind of itchy, biting rash on the fold of my inner arms. Google eczema or food allergy. (and fyi to save you a lot of headache if it is a corn allergy - you could be reacting to anything with corn, which is pretty much all processed foods, table salt, glue, shampoo, toothpaste, etc. etc. etc.! I REALLY hope that's not what it is!) Good luck.