Why does my mouth itch?

I was just wondering if anyone else had a theory. Wheneverer I eat bananas, kiwis, melons, and cubers(among other things) my mouth starts itching. Its usually just the top of my mouth, and its not severe, but does itch. I was thinking it was an allergy but the symptoms I found don't seem to match. Any ideas? And yes, I know I should see a doctor. But just wanted some other opinions as well. Thanks!