Just because your son "tests high" for food allergins, doesn't mean has has to stop eating them all together.
My son just turned 8 on July 7th and has been allergic to most food since he stopped nursing at 7 months old. His allergic reactions were almost instantanious once the food passed his lips. Itchy ears, red, watery eyes, scratchy throat, then projectile vomiting of mucus and food bits. (of course, it took us a while to figure all of this out.) Many blood tests and hospital visits later, we found out that everything we were feeding him from his formula to the mashed peas we making him sick. (Talk about feeling like an awful mother!)
He has since outgrown most of these food allergies. He was unable to have any milk based products, soy based, including hydrogenated soybean oil, seafood, eggs, or anything with any kind of nut products.
He still "tests high" for peanuts, eggs and fish, but he can actually have salmon, shrimp, crab, and halibut. He tests low for these particular foods, and doesn't have any kind of reaction to them. We haven't tried the peanut allergy test with the allergist yet, and just avoid peanut based products all together. He can actually eat eggs if they are cooked in a cake or something like that. He even ate part of a scrambled egg for the first time this weekend. His fear of having a reaction has kept him from trying new things. He always asks, "Can I have this? Am I allergic to it?"
If your son is not having any sort of reaction with milk or wheat based products, then find out what your allergist might suggest with regards to diet. If your son is used to having milk products and wheat based products, then it will be a bit harder to change eating habits cold turkey. Does he have certain foods that elicit a reaction? Certain people can build up a tolerance for certain foods that they are "allergic" to.
Switching to foods that do not have milk bi-products, wheat bi-products or enzymes in them will require A LOT of reading labels on your part. The best way to do this, of course, is to only buy fresh food and prepare it yourself. While this can be done (been there, still do it for certain things) it's not the easiest or quickest, or even the most cost effective depending on where you live.
The internet is a wealth of information for recipes and suggestions. I've spent many hours pouring over recipes for icecream without eggs!
Type in "food allergies to milk and wheat" and Google it. You'll be amazed at what is out there. Good luck!