It is very common even without an allergy to it. It is because it is high in citric acid and just like any acid it burns. The severity of it depends on the level of acid the piece of fruit contains. Just like everything in nature, each piece is different.
prob cuz you're allergic to the citric acid :-p i had probs with it when i was younger, but i got a rash. DS gets a rash as well from citrus. my sister gets the itchy throat. as long as it doesnt effect your breathing you're ok. if you can handle the scratch then eat away lol