It could be related to a latex allergy, or to a birch or ragweed allergy. This past summer, I discovered that I have developed an allergy to avocado, which is related to a birch allergy (to which I must be allergic because my seasonal allergies are worst when birch pollen is high). It's called an Oral Allergy Syndrome--my whole mouth starts to feel really itchy, and it does burn a bit.
http://en.wikipedia.org/wiki/Oral_allergy_syndrome