Firstly, I'm sooo sorry - this allergy thing can make you crazy. I agree with the other two posters. The RAST numbers are only one small piece of a much larger puzzle. My DD also tests positive for all sorts of foods she tolerates. She doesn't react to some foods she has a high RAST to, and is more sensitive to foods with low RASTs. I also have a friend whose daughter has a very low peanut RAST but is highly sensitive. I'm not sure of the science, but it drove me nuts for a long time doing eliminations and then challenges. I used to have so much anxiety about the RAST tests but have learned to watch HER and not the tests. I understand scratch tests can be just as mind-boggling. The only real test is how the child reacts.
In my (non-doctor) opinion, I'd keep your son on all the foods he tolerates. We've also had huge success with cooked versions of milk and egg - heat breaks down the protein and makes it more tolerable. That has changed her life (and mine as family cook) dramatically.
Good luck! I know it's just awful. Hugs!