There are so many websites on line that deal with recipes that your son can have and your family. You family can change somewhat with the way they eat. There are recipe books out there too.
Milk isn't good for the body anyway, so that's no problem there. There are plenty of alternatives to 'milk' that are much healthier. You can even buy a soyajoy milk maker and make milk in a matter of 15 minutes cheaper!
As far as wheat goes, there are many people that can eat wheat as long as it is sprouted first. You can always sprout your wheat first and then grind it up to make your own bread for him. I'm sure a breadmaker will make it easier if you aren't used to making your own bread.
Corn is pretty common in LOTs of people's allergies. There are many people allergic to corn and corn products and don't even know it. Corn products are in a lot of processed food, etc. So it sounds like you'll be getting your family healthier thankfully to your little one (which is great!) Good luck!
Another note though, when people have a lot of allergies, it typically due to an overactive immune system. You can help with that by giving him some herbs, typically a combination of astragulus and marshmallow root (Immucalm found at www.herbsfirst.com). I gave that to my oldest when he developed allergies to animals. It kept the problems away when he was exposed to animals.