I do not recommend, at this stage, cutting out your sons carbohydrates. It appears he has a very limited diet to choose from, and is growing. Perhaps cut down a bit on carbs and up the protein, and then wait and see what his GP says, as further tests are needed to find out what, if anything, is going on.
Likewise, our son has steroid medication for his eczema. I see from another post that your have stopped this (post #19)? Please dont continue to stop this. His distress with his eczema will not help the situation and could be harmful to his treatment of it.
Is it possible, from what you have said, that your son has Apergers/Autism?
You also said that your son is needle phobic, and the fear of testing can also put his blood sugars up.
He is only 8 years old. Cuspian means he is so close to any borderline that he may or may not be type 2 pre-diabetic. Either way, let his GP sort any diagnosis out before changing anything, and there is plenty of time to deal with anything his further tests and investigations may show up.