Yes. A food allergy or a food intolerance can cause other problems like a yeast infection on his bottom. Each food allergy or intolerance presents different symptoms in every person. Because it can be difficult to quickly pin down which food is causing the problem, I recommend the using the elimination diet to determine if eggs is really the problem. I have detailed out the procedure below.
Day 1. Remove all eggs and egg products from your son's diet. The easiest way to do this is to stop feeding him all processed foods for a bit.
Day 2. Watch him for the next 4 days while on the egg-free diet; has the rash changed, disappeared, gotten worse? Track all of his changes in symptoms in a journal so you can see the overall trend over time.
Day 5. Introduce one cooked egg at breakfast and track the changes, if you don't see any symptoms, give another cooked egg for lunch, and track the changes again, if you don't see any symptoms, give a third cooked egg for dinner. On this day you don't want to give him any processed foods, only whole eggs, so you are testing just for eggs and not anything else that may be in the processed foods.
Day 6. Go back to the egg-free diet for the next 4 days and track your son's symptoms.
Here's the science behind the elimination diet: It takes four days for foods to be completely processed and eliminated from the body. So, you need to cleanse your son's body of the suspected allergen before you can test and get accurate results. Then you only test for one day and track all results for the next four days. Not all reactions are immediate, symptoms can appear anywhere between 20 minutes after ingesting the food and up to four days later. That's why keeping a journal is so important.
If after the elimination diet he still has the rash and it has not improved, you may want to look at other highly suspect foods. These include:
dairy
wheat
soy
Other less common foods that can cause reactions include the following, but are not limited to:
tomatoes (very acidic, especially home-grown tomatoes)
citrus
rice (unusual, but some people do react to this food)
garlic
strawberries
If you have any questions about the elimination diet please message me, I'm happy to help. Also, you might want to contact a pediatric allergist and see what they have to say about suspected food allergies or food intolerances.
Good luck.
C. J.