K.K.
All my kids were sensitive to citrus fruits (oranges, strawberries, etc) and would get a rash on cheeks (both sets!) when they ate them and would have sensitive bottoms from diarrhea. I would just limit intake of those until they are about 3 years old - that's when mine kind of outgrew the sensitivity. The hardest thing is to get the grandparents to cooperate... My kids would go over to my mom's or my MIL's house and they'd feed them tons of fruit salad and wonder why they all had messy diapers!