Birch Pollen Allergy?

Has anyone had any experience with Birch Pollen Allergies? We started my baby out with outmeal cereal at 4 months because our pediatrician said she looked ready and she was showing all the signs of readiness. She did great with oatmeal cereal, no problems. Then we tried pears, and within 30 seconds of trying the pears, her face got all red and splotchy especially around her eyes. We called her doctor and tried it one more time the next night, and the doctor said to hold off on pears for a month, then try them again. In the meantime we've tried sweet potatoes and pumpkin which she did great with, no problems. Tonight we tried apples though and she had the same reaction as the pears. I'm going to call her doctor tomorrow, to see what we should do. In the meantime though, has anyone had any experiences with reactions like this to pears or apples? My other two never showed any reactions to any foods, so this was really unexpected.