Most Africans are lactose-intolerant - the tolerance gene evolved twice, once in Western Asia (hence most Europeans are tolerant) and once among the Fulani of West Africa. If you don't have ancestors from one of those two groups, milk gives you the runs. But lactose intolerance is in no way an allergy.

It can't hurt for your hubby to try total exclusion of wheat and related grains for a while. Usually you'll know if it'll help in a week or two, though it can take as long as a month to see positive results.

The worms thing is well past speculation now and into the realm of things you can get a research grant for. There is some recent work on the mechanism: it seems to be indirect, with the worms (or absence thereof) causing a drastic change in the gut flora - the gut bacteria are what really control the allergic response.