I think it's wonderful that you're thinking outside the box and willing to do something to better the health of your child. What will happen is you will create a healthy foundation for him to have wonderful eating habits for life.
First, get him off processed foods. Nearly everything he's eating is constipating and the biggest culprit is dairy. The dairy council has spent millions on advertising and 'tests' to make society believe that cows breast milk is healthy for humans. Nothing could be farther from the truth. It causes so many problems I don't know where to begin but constipation, obesity and diabetes are high on the list. Check out www.notmilk.com
Next, if you're giving him rice, make sure it's brown, white has about as much nutrition as a paper napkin. Lightly sautee, pan fry or steam some fresh veg and put it over some rice. Make a sauce mixing some tahini with lemon juice and herbs and spices of your choice or cook it up with a dash of tamari (healthier soy sauce)
Beans are great too.
If you're giving him cereals in the morning and they're crunchy use a nut milk instead of cow milk.
My daughter loves leftover grains with nut milk heated up with a banana (organic) for breakfast. Sometimes I'll make her a fruit smoothie for breakie but not too often b/c it weakens the system.
Dinner? sweet potatoes, squash, mixed greens, toasted sesame seeds on top for extra absorbable calcium, string beans, collards, zucchini, artichoke, peppers, cauliflower.
Make a bean sauce, make a veg sauce, kids love sauces to dip stuff into. It's fun
Sticking with nature is the BEST way to have your body run naturally.
Also, make sure you give him plenty of water to flush out toxins too.
Good luck!
Oh, by the way, get yourself on this way of eating too.
NO SUGAR either