It depends on what he is sensitive to. Is he lactose intolerant (meaning he lacks the enzyme lactase that digests the milk sugar lactose)? If so ( and from the symptom picture you describe that may be it) then raw milk might very well be the answer. My dh is lactose intolerant and can eat any raw dairy just fine...no gas, diarrhea any thing! Raw milk contains the enzyme lactase, but it is killed by pasturization.
However, if your child is allergic to the milk protein casein, ( meaning the casein causes a system-wide immune response that can manifest in many different ways, from GI symptoms, to sniffles, to sleeplessness, to mood, to musculo skeletal things) then raw milk is still going to cause that response.
If you dont know wich one you son has, I would try raw milk and see what happens

Hope that helps
Tanya