Actually, a lot of homeopathic remedies have lactose base (oscillococinum is also coming to mind right now) and most of the Hylands tablets do unfortunately. However, you should know that many MSPI babies do fine with lactose - it's usually the milk proteins that bother them. It's quite rare for a Caucasian baby to be lactose intolerant in fact. Possible but more unusual.
Has he reacted negatively to the Hylands? If not, I'd continue to use them. If you are concerned, you might be able to find single ingredient remedies (like camomila, belladona, etc) without lactose base.