You can google nut allergies and I am sure a ton of sites will come up as food allergies are becoming more and more popular with children.
Go to your local Whole Foods Market or Henry's Marketplace or Sprouts and they will have a bunch of packaged items that are nut or allergen free. One brand that I use a lot (my kids don't have allergies, but I buy this product because it is cassein free and has no artificial sweeteners) is called Namaste. They make mixes for cakes, muffins, pizza crust, etc.
I do have some food allergies to things like chocolate, almonds, and apricots so I was a label reader from a young age. And now with my kids I read every label before I buy something packaged. Even if it says "organic", I am still checking the labels for Trans/hydrogenated fats/oils, high fructose corn syrup and other artificial sweeteners, aspartame, etc. You will also need to check the labels of anything you use in your home to clean with or personal hygiene items that anyone in your family uses as many of them will contain nut oils.
I think on the Henry's and Whole Foods website you can do a checklist of allergy items to avoid and then you can print out a list of items that you can buy at their store. I did that once for my friend whose daughter is severely allergic to almost everything.
To be safe, I would provide all your sons snacks/food whenever he will be away from you for meals. That way you know exacly what he ate and where it came from.
And be careful when you go out to eat. A friend of a friend has two children who are severely allergic so when they go out to eat, she calls the restaurant in advance and checks with the head cook/chef about the ingredients they use, then she calls the suppliers of the items all to make sure that her kids won't have an allergic reaction to the food.
It's a lot of work, but you have to do it.
You should also check out a food allergy support group. I know there is one here in San Diego and I am sure there are tons of them online.
Good Luck!