A.,
Part of this is the craving for - SUGAR - and your 4 year old up until now has gotten what he wants during the day.
Look up the GAPS diet - and find a GAPS diet group somewhere near you - and start reading as much as you can without neglecting your kids!
As far as being in school, I would - and this is ME - take him out. It is far too stressful to have a major dietary change where *everyone else around him is eating essentially contraband* and reminding him of what he cannot have. homeschooling for a half a year, a year, until he can get a leg up on functioning in this diet (and kicking you is just small beans!) may be the saving grace he needs. Your warm, loving attention during the day vs the inattention to detail at school may help him more than anything else. Leaving him hanging there on his own. I know. day job. you have to weigh - functioning baby boy vs extra income. And you will come to view it as that. What can you cut out of your budget to keep your baby sane?
Plus - you don't know that he isn't getting it at school. (Please, can I have a bite of your mac & cheese?)
Cravings aren't about sanity. it's about what your body is used to. And the body wants to get back where it was. Because it was comfortable there. Yes, this is *JUST*LIKE*DRUGS*. What they don't tell you is: sugar is harder to 'come off of' than drugs. It is not only ubiquitous, it is addictive. No kidding. Look it up.
Gluten free isn't a diet for sometimes with periods of 'oh hey, I can have that for just once.' You know that. Expecting your 4 year old to reason with that and know how to work with it - and deal with it effectively - and everything that goes with it - well, like that's saying he can stand up in court and give testimony. Nope. Nada. Can't do it. So don't make him. don't hurt him with those expectations.
Cravings are really, very, nasty feelings. They are very real. You can't wish them away.
His best bet is to find recipes that are TASTY (and he might like pesto - finding a gluten free pesto is HARD but very worth it! You will likely have to make your own.) Have stuff on hand that he can snack on. He's a growing boy. Won't be 4 forever. will get taller. Will get a bigger appetite. Will get cravings for a long, long time, and they WILL upset the applecart if he is underprepared.
don't forget - gluten comes in ODD places. Look them up. Know them.
cheeses - like goat cheese - you have to find grass-fed animal cheese.
there is a product out there called 'chreese'. It's fake. Iknow. It still tastes good. Don't use it until the cravings go away, or not at all. Because it can trigger MORE cravings for the real deal. Very tasty stuff. Very expensive.
There is so, so much your doc didn't give you info for - and you will need to do a lot of research to keep him on this diet.
If you do decide to homeschool - Waldorf education is a very effective way to go. I think there are some in your area, but may be not close to you. Check it out. It is a schooling path that is very open to the dietary change path.
There is so, so much more. You'll be thankful you asked here. You'll ask other places too. Keep on asking. the questions will start you on a path for better for your whole family.
Oh and BTW - if you haven't given up all the stuff he can't have - and are still keeping it in the house - expect it gotten into at some point in time. Give it up. Go the diet with him. It's hard. but you know, it is SO much more healthy for you and your family in the short AND long run. Researching it will help you understand that too.
Good luck, and don't stop with what I've written,
M.