Just a little update if you're interested...
I went to see a friend of a friend, who does acupuncture and kinesiology. He did his allergy testing on both me and my baby boy. They do the muscle testing thing where you are unable to hold up your arm if you are sensitive to the food. Don't understand it very well. But anyway, I came up as being sensitive to calcium, eggs and gluten. My DS came up as being sensitive to potatoes, tomatoes, soy and peanuts - all of which he's had heaps of and I have never noticed any reaction. And DS was clear for anything to do with dairy.
I found it all really surprising - not at all what I was expecting to hear. I am unsure whether to trust the results or whether I am a complete skeptic. And I don't know where it leaves me with his potential dairy allergy... According to this test he should be fine with it... and not with soy (very ironic as when we had to supplement my BF with formula due to low supply we used soy to avoid risk of dairy allergy).
I'm wondering whether to try some more dairy (not the rusks, but something different like some baby food with some dairy in it). If he seems to have a reaction maybe I'll go to my doctor (I have a new one now - yay) and go through those channels to get him tested.
In any case the kinesiology was an interesting experience