Unfortunately these symptoms are common indicators of food intolerances, especially lactose intolerance. Some of the natural acids in fruits may cause a rash around the mouth, but is not an allergy, and diarrhea may be caused by excess sugar in fruit juice, also a non-allergic response. If you suspect a food allergy, keep a diary for several days of what your child eats and drinks and what reactions you observe . Take this account to your pediatrician to help him with his diagnosis. As you go about increasing the variety of foods in your baby's diet, do it with an eye out for those foods that are most apt to cause a problem.
Food allergens are usually proteins.
The protein in cow's milk, egg, peanut, fish, wheat, and soy are the most common food allergens, although any food may cause an allergic reaction. An allergy to a particular food may indicate an allergy to an entire food family, known as cross reactivity. Fortunately, most children do not suffer from cross-reactivity and are allergic to only one or two foods. If you discover that your child suffers from multiple food allergies, you would be wise to engage the help of a pediatric dietitian who can help you create a diet that eliminates the offending foods without causing nutrient deficiencies while still offering variety. Once diagnosed, the only way to treat a food allergy is complete elimination of the food.