Have you tried Veggie slices, a cheese substitute made out of soy?
If your son can tolerate a small amount of dairy, try Kraft cheese as it contains just a small amount of lactose and you child may tolerate it without any symptoms.

Please note that lactose intolerance is not an allergy.  It is intolerance to the sugar lactose found in dairy.  Therefore, symptoms triggered by ingestion of lactose, although uncomfortable, are not life-threatening and resolve once the lactose leaves the body.

You may try the cookbook "Lactose free and loving it" as it has a collection of recipes that use delicious dairy substitutes.  The cookbook is available at amazon.com.

I'm sorry to hear about your son's diagnosis.  Lactose intolerance is annoying but resolvable by staying away from certain milk products which worsen the condition.  There are also different levels of intolerance.  Some can have little lactose and others, none at all.  In addition, have hope, because intolerance can go away with age as well.  When I was five, I was lactose intolerant, and my parents gave me soy milk, rice milk, and dark chocolate instead of milk chocolate.  Later, I was able to digest milk products. It's not all negative to cut out dairy; as long as your son is receiving protein and calcium in other ways he should be fine.  
The following is an article detailing your son's condition
http://www.education.com/reference/article/Ref_Milk_Kids_Lactose/
I hope this helps!
Rachna

Redwood City Mom,

I was also diagnosed with lactose intolerance at a young age.  Some people with lactose intolerance cannot eat any dairy at all, whereas some can eat different types of dairy in moderation.  It is good to figure out what works for your son.  Depending on the severity of his lactose intolerance, he may be able to eat some forms of cheese.  I found that milk, ice cream, and the heavy yellow cheeses (like cheddar cheese) made me the most sick, whereas, light yellow cheeses like parmesan and mozzarella had a little effect.  It is good to figure out whether he can eat some kinds of cheeses with medication, or whether he totally needs to stamp out dairy from his diet.  Depending, he may be able to eat macaroni and cheese if it is made with a light, non-cheddar cheese.  Also, most pizzas are made with artificial cheese – he may be able to keep this staple in his diet.

An over the counter medicine that worked for me was Lactaid.  It can be taken in pill or chewable form with the intake of dairy.  Lactaid milk and soy milk are also good substitutes for regular milk.   I am glad he enjoys soy substitutes.  These products are infused with calcium and vitamins, which will provide him with the nutrients he would have been lacking in his diet.  Tofutti, a cream cheese substitute, is another great product you should try. http://www.tofutti.com/btcc.shtml  

When looking for dairy substitutes, be aware that vegetables and fruits may irritate him if eaten in abundance.  Carbs and meats are the easiest to digest.

When diagnosed with lactose intolerance at a young age, ten years later I learned that it was the beginning of a different condition all together.  It was not lactose intolerance afterall.  Be aware that the symptoms of lactose intolerance can be the early symptoms of other conditions, such as Crohns, colitis, or gastric reflux disease.  Definitely watch him and take him to a pediatric gastrointestinal doctor if he gets more sick.  He also may grow out of his lactose intolerance completely.  It really depends on each individual case.    You seem like a diligent mother, and I am sure you will take good care of him.

I hope this helps and your sons’ condition is controlled.

Best wishes,

Hayley