What is making me allergic to fruit and how do I treat it?

Any time I eat fruit (a single strawberry, a couple bites of an apple, a piece of banana, gs, etc.) or drink real fruit juice (not as intense with citrus fruits but still sensitive to those) my face feels cold and clammy and I feel like I'm going to throw up. This greatly limits my diet and since I can't stomach regular sugar very well I like to fix my sweet tooth with fruit. Sometimes I just put up with being sick to enjoy a good snack but I'd like to know what exactly about the fruit am I reacting to and how can I treat it?