My daughter, who is now 6-1/2 yrs. old, and I, are both lactose intolerant. People who are lactose intolerant CAN USUALLY handle cheddar cheese, yogurt, and sometimes fat-free milk. My daughter and I eat a lot of yogurt, and we eat a good bit of cheddar cheese. My daughter was diagnosed lactose-intolerant when she was a baby. I was breast feeding her for the first 2-1/2 mos. then I QUIT lactating. It was a natural occurrence, and one that my doctor could not explain. So, we had to put my daughter on formula. The first formula tried was the standard Similac with Iron. My daughter had severe constipation (to the point of impaction at times) and was always throwing up. The Dr. said she was probably lactose-intolerant, so he was going to switch her to Pro-Sobee, which is a soy formula. Well, that gave her extreme gas and made her irritable, so he said she was sensitive to soy, and he switched her to Lacto-Free formula and diagnosed her with lactose intolerance. She has drank Lactaid from the age of 1 to the age of 5. At 5, WIC was no longer supporting her with her milk, and I couldn't always afford nearly $4 for a half gallon of milk, so I tried FAT-FREE milk. She was able to stomach FAT-FREE and so am I, although we can't have too much of it.
You can talk to your Dr. about this, but if you want to continue to give him whole milk and you can't afford to put him on Lactaid whole milk, then there are 2 solutions out there. One is there is a supplement that you can buy over the counter at Walmart or a pharmacy. It's called Lactobacillus. This is the bacteria that digests lactose, which is a milk sugar that we can not digest on our own sometimes. It's a tablet, and it can be crushed. (I am a nurse, and we used to give this to a tube fed patient who could not be switched on his feedings, but he was lactose intolerant and couldn't stomach the feedings on his own, so the Dr. ordered the supplement and it helped him greatly!) Also, there is an over the counter treatment that you can buy called Digestive Advantage Children's Lactose Intolerance
and also there is Lactaid Fast Act.